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- Unanticipated reactivity toward nucleophilic attack in the synthesis of saccharyl-1,3,4-thiadiazolyl conjugates: structure and mechanistic insightsPublication . Guerreiro, Bruno; Carvalho, Daniel F.; Coelho, Jaime A. S.; Frija, Luís M. T.; Paixão, José A.; Cristiano, Maria de LurdesAlong with the synthetic process optimization of 3- [(5-methyl-1,3,4-thiadiazole-2-yl)sulfanyl]-1,2-benzothiazole 1,1- dioxide (MTSB), a selective copper chelator with potential interest in cancer chemotherapy, the unprecedented isolation of a novel compound, 3-(1,1-dioxidobenzo[d]isothiazol-3-yl)-5-methyl-1,3,4- thiadiazole-2(3H)-thione (BMTT), evidenced an unexpected reactivity of the starting 5-methyl-1,3,4-thiadiazole-2-thiol. To shed light into the reaction mechanisms, quantum chemical calculations were conducted at the M06-2X/def2-TZVPP/PCM- (THF)//M06-2X/6-31++G(d,p) level of theory. The results conjecture the formation of BMTT from nucleophilic attack of the nitrogen at position 3 of the thiadiazole ring, involved in an Sto-N delocalized thiadiazole-2-thiolate structure, which is thermodynamically more favorable in the presence of Na+ . Experimental assays refute a plausible concerted 1,3-sigmatropic S- to Nrearrangement of MTSB that would lead to BMTT. Hence, contradicting the nucleophilicity indices of sulfur (from thiol) and nitrogen atoms of 5-methyl-1,3,4-thiadiazole-2-thiol, it is believed that an exotic nucleophilic attack by the nitrogen at 3-position of this reagent to the sp2 carbon in position 3 of pseudo-saccharyl chloride should take place. Besides, the crystal structures of the MTSB and BMTT hybrids were investigated in detail by X-ray crystallography.
- Using ECG-derived respiration for explaining BOLD-fMRI fluctuations during rest and respiratory modulationsPublication . Esteves, Inês; Rodrigues Fouto, Ana Lúcia; Ruiz-Tagle, Amparo; Caetano, Gina; Figueiredo, PatríciaRecording physiological signals during fMRI is valuable for multiple purposes but often requires additional setup, increasing complexity and participant discomfort. This is particularly challenging in simultaneous EEG-fMRI studies, which typically already include electrocardiogram (ECG) recordings. Here, we aim to leverage the known modulation of ECG by respiration to obtain an ECG-derived respiration (EDR) signal without extra equipment. We acquired EEG-fMRI data from 15 healthy subjects during resting state and two respiratory challenges (slow-paced breathing and breath-holding), with simultaneous ECG and respiratory recordings. Multiple methods were used to extract EDR signals, and the results were evaluated by comparing them with recorded respiration and assessing the quality of physiological regressors for denoising and cerebrovascular reactivity estimation. Amplitude-based EDR methods showed lower correlations with respiration, likely due to ECG distortion in the MRI. Nevertheless, coherence analysis showed that EDR preserved the relevant spectral content. EDR-based regressors were similar to those obtained from measured respiration. Notably, a method based on heart rate variability performed best overall, yielding physiological noise correction and reactivity estimates comparable to those using recorded respiration. Our results demonstrate that meaningful respiratory information can be extracted from ECG within the MRI environment, benefiting EEG-fMRI studies when respiration cannot be reliably recorded.
- The prevalence of two known pathogens of atlantic blue crab callinectes sapidus (Rathbun, 1896) in coastal adriatic, aegean sea, and atlantic iberian coastPublication . Schott, Eric; Sćepanović, Marina Brailo; Maršić-lučić, Jasna; Pares, Olivia; Zhao, Mingli; Hrabar, Jerko; Glamuzina, Luka; Pećarević, Marijana; Grdan, Sanja; Encarnação, João Pedro da Silva; Morais, Pedro; Pešić, Ana; Cetković, Ilija; Glamuzina, BrankoIn the Mediterranean Sea, the abundance of the invasive portunid crab, Callinectes sapidus, has dramatically increased in recent years. This raises concerns about damage to ecosystems, but also offers opportunities for exploitation of a new fishery. Newly invasive species may escape from pathogens in their native range, may introduce new pathogens, or can become host to endemic pathogens. Understanding these factors is important for predicting or managing natural resources in the invaded range. Using quantitative PCR methodology, this study investigated the prevalence of two pathogens common in C. sapidus in its home range of North America: the reovirus CsRV1 and the protozoan parasite Hematodinium perezi. In crabs collected from Aegean, Adriatic, and Atlantic waters, the CsRV1 virus was not detected. In contrast, the parasite H. perezi was found in crabs from all areas except the Aegean Sea. Sequence analysis of the H. perezi ITS1 gene indicated that the strains observed are most related to genotypes already described in Europe and the Mediterranean, and not to strains from the Americas or Asia. The arrival of new species and new potential pathogens is ongoing through transfer of ballast water to the Atlantic and Mediterranean. Although systems are in place to exchange or inactivate ballast water, it is advisable to continue and expand surveillance for pathogens in introduced species, to inform management of movement of these species between regions.