ZnO nanoparticles as a potential biolabel for bioimaging applications

In order to better understand biological processes and thus understand and find better treatments for diseases, it is essential to have suitable bioimaging methods. One of these methods is confocal mi-croscopy, which uses fluorescence. To confer fluorescence and thus study biological samples, many different types of fluorophores can be used. One of these types of fluorophores are nanoparticles, which have several advantages in compar-ison with other fluorophores. However, the nanoparticles most traditionally used for obtaining biolog-ical images use cadmium, which is very toxic. For this reason, different materials have been studied in order to conceive nanoparticles with high fluorescence and low toxicity, of which zinc oxide (ZnO) nanoparticles have generated considerable interest because, in addition to their good optical properties, these are also considered safe, being used in various areas and products such as sunscreens, cosmetics, and food packaging. Moreover, the ZnO nanoparticles are still very promising in medicine to be used in the fight against cancer and have antibacterial properties. However, as ZnO nanoparticles have a high band gap, their fluorescence mainly occurs when they are irradiated with low wavelengths, which are not commonly used in confocal microscopy or in biological samples. Due to this, throughout this thesis, ways of increasing the fluorescence of ZnO nanoparticles (by using longer wavelengths) will be studied, namely by doping them with europium, as well as the effects that different syntheses/doping concentrations influence other properties of these nanoparticles (such as morphology and crystallinity). To finalize, the fluorescence conferred to biolog-ical samples through the use of the synthesized nanoparticles will also be analyzed through confocal microscopy. The obtained results were compared with those obtained with a commercial fluorophore.De forma a melhor entender processos biológicos, e assim perceber e encontrar melhores trata-mentos para doenças, é muito importante ter bons métodos para a obtenção de imagens biológicas. Um desses métodos é através de microscopia confocal a qual usa fluorescência. Para conferir fluorescência e assim estudar amostras biológicas, há muitos tipos diferentes de fluoróforos que podem ser usados. Um desses tipos de fluoróforos são nanopartículas as quais possuem várias vantagens em com-paração com outros fluoróforos. No entanto, as nanopartículas mais utilizadas para a obtenção de ima-gens biológicas usam cádmio, apresentando uma elevada toxicidade. Por este motivo, outros materiais têm sido estudados de forma a ser possível obter nanopartículas com elevada fluorescência e baixa toxicidade, sendo o óxido de zinco (ZnO) bastante interessante pois, para além das suas boas proprie-dades óticas, as nanopartículas de ZnO são também consideradas seguras sendo usadas em diversas áreas e produtos como, protetores solares, cosméticos, e embalagens para comida. Para além disto, as nanopartículas de ZnO, mostram-se ainda muito promissoras em medicina para serem usadas na luta contra o cancro e apresentam propriedades antibacterianas. No entanto, devido ao elevado band gap das nanopartículas de ZnO, a sua fluorescência ocorre principalmente quando estas são irradiadas com baixos comprimentos de onda, os quais, por norma, não são usados em microscopia confocal nem em amostras biológicas. Desta forma, ao longo desta tese serão estudadas formas de aumentar a fluorescência das nanopartículas de ZnO (para maiores comprimentos de onda), nomeadamente através da dopagem destas com európio, assim como os efei-tos que diferentes sínteses/dopagens influenciam outras propriedades destas nanopartículas (como morfologia e cristalinidade). Por fim a fluorescência conferida a amostras biológicas através da utili-zação das nanopartículas sintetizadas será também analisada através microscopia confocal, tendo sido também comparadas as propriedades obtidas com as de um fluoróforo comercial

Efficacy and safety of primary, early and late needle-knife fistulotomy for biliary access

European Society of Gastrointestinal Endoscopy recommends needle-knife fistulotomy (NKF) as the preferred precut technique. However, there is little information on whether NKF performed at different times is associated with different success and adverse event rates. We compared the outcomes of 3 different timings of NKF. This was an observational study conducted at 4 institutions and this was a retrospective analysis of prospectively collected data. We included 330 consecutive patients submitted to NKF attempt for biliary access. Patients were divided into three groups: NKF as an initial procedure for biliary access (group A, n = 121); early NKF defined as after 5 min, 5 attempts, or 2 pancreatic passages (group B, n = 99); and late NKF: after at least 10 min of unsuccessful standard biliary cannulation (group C, n = 110). We assessed the success rate of biliary cannulation at initial ERCP, time to perform NKF until biliary cannulation, overall biliary cannulation rate (second ERCP when initial failure), adverse event rate, and predictors of post-ERCP pancreatitis (PEP). The initial cannulation rate was 98%, 91% and 94% for groups A, B and C respectively, p = 0.08, whereas overall biliary cannulation rate was 100%, 95% and 98%, p = 0.115. The adverse event rate/PEP was 4.1%/2.5%, 7.1%/4% and 10.9%/8.2%, for groups A, B and C respectively, (p = 0.197 and p = 0.190). Median time for creating the fistula was A = 4.0 min, B = 3.2 min, and C = 5.6 min, p < 000.1. Each additional minute spent attempting cannulation increased the odds ratio (OR) for PEP by 1.072, and patients with 3 or more risk factors for pancreatitis had a higher chance of PEP. In conclusion, the timing of NFK does not appear to influence success rates but late NFK is associated with a higher time to create a fistula and an increased risk of pancreatitis. Primary NFK is associated with a high rate of success and a low rate of PEP and deserves additional investigation.publishersversionpublishe

Vitamin D-related polymorphisms and vitamin D levels as risk biomarkers of COVID-19 disease severity

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Vitamin D is a fundamental regulator of host defences by activating genes related to innate and adaptive immunity. Previous research shows a correlation between the levels of vitamin D in patients infected with SARS-CoV-2 and the degree of disease severity. This work investigates the impact of the genetic background related to vitamin D pathways on COVID-19 severity. For the first time, the Portuguese population was characterized regarding the prevalence of high impact variants in genes associated with the vitamin D pathways. This study enrolled 517 patients admitted to two tertiary Portuguese hospitals. The serum concentration of 25 (OH)D, was measured in the hospital at the time of patient admission. Genetic variants, 18 variants, in the genes AMDHD1, CYP2R1, CYP24A1, DHCR7, GC, SEC23A, and VDR were analysed. The results show that polymorphisms in the vitamin D binding protein encoded by the GC gene are related to the infection severity (p = 0.005). There is an association between vitamin D polygenic risk score and the serum concentration of 25 (OH)D (p = 0.04). There is an association between 25 (OH)D levels and the survival and fatal outcomes (p = 1.5e-4). The Portuguese population has a higher prevalence of the DHCR7 RS12785878 variant when compared with its prevalence in the European population (19% versus 10%). This study shows a genetic susceptibility for vitamin D deficiency that might explain higher severity degrees in COVID-19 patients. These results reinforce the relevance of personalized strategies in the context of viral diseases.This project was supported by the “Fundação para a Ciência e Tecnologia”, program “Research 4 Covid-19 Apoio especial a projetos de implementação rápida para soluções inovadoras de resposta à pandemia de COVID-19”. It was also partially supported by each institution.info:eu-repo/semantics/publishedVersio