Dynamics and Development of Extensively Drug-resistant Tuberculosis, Portugal

Abstrat publicado em: http://www.pasteur.fr/infosci/conf/sb/tuberculosis2012/images/TB2012-Program-Abstract-book-LD.pdfThe development of multidrug-resistant (MDR) and extensive drug-resistant (XDR) tuberculosis(TB) combined with subsequent transmission constitutes a serious threat to the effective control of tuberculosis in several countries. Lisbon Health Region, despite great progresses in TB management still presents a high number of MDR/XDR-TB cases. The development of this type of resistance is the result of adaptative selection of Mycobacterium tuberculosis strains that acquire and accumulate specific mutations at specific genes. The presently known mechanisms of drug resistance include the modification or overexpression of drug targets, inactivation of drug- activator enzymes and overexpression of drug-modifying enzymes. Although the molecular basis of resistance of MDR/XDR-TB strains circulating in Lisbon has already been addressed in different studies, the dynamics or mode of resistance acquisition that have lead to the different circulating strains is still partially unclear. In the present study we have genotyped and screened a set of 44 MDR/XDR-TB isolates for mutations in tlyA, gyrA, rrs and eis genes. We have determined the most prevalent mutations found in each gene to be Ins755GT in tlyA, A1401G in rrs, G-10A in eis and S91P in gyrA. Two genetic clusters previously known to be associated with XDR-TB were detected, Lisboa3 and Q1, containing 27 and 17 isolates, respectively. Lisboa3 strains isolated in the 90’s with the same mutational profile of recent XDR-TB Lisboa3 strains were found, emphasizing the ancient XDR-TB problem in the region. Also investigated was the resistance level conferred by eis G-10A mutations, revealing that eis G-10A mutations may result in an undetectable AMK resistance. We concluded by analyzing the mutational distribution found by genetic cluster that in Q1 cluster two mutations, gyrA D94A and rrs A1401G, were enough to ensure development of XDR-TB from a multidrug resistant strain. Moreover, in Lisboa3 cluster it was possible to determine that the development of kanamycin low-level resistance mediated by eis promoter mutations was at the origin of independent emergence of several XDRTB strains that can be discriminated within Lisboa3 genetic cluster by tlyA mutations

Dentin Bonding: SEM Comparison of the Resin-Dentin Interface in Primary and Permanent Teeth

Previous studies have suggested minor differences between primary and permanent teeth in terms of dentin composition and morphology. Other reports indicated lower bond strengths of resin composites to dentin of primary teeth compared with dentin of permanent teeth; however, no information is available regarding differences in the micromorphology of the resin-dentin interface that may explain these lower bond strengths. Therefore, the purpose of the present study was to compare primary and permanent teeth in terms of the thickness of the hybrid layer developed with two bonding systems. Our hypothesis was that bonding differences previously reported between primary and permanent dentin would be reflected in hybrid layer differences observable in SEM analyses. Twenty human extracted and non-carious teeth were divided into 4 groups: 5 primary and 5 permanent teeth restored with All-Bond 2/Bisfil P system; and 5 primary and 5 permanent teeth restored with Scotchbond Multi-Purpose/ZlOO. The sample area available on each tooth was divided for the two dentin conditioning times (7 and 15 sec). Measurements of hybrid layer thickness were performed by means of SEM at xl3,000. The results of this study indicated that the hybrid layer produced is significantly thicker in primary than in permanent teeth (p = 0.0001), suggesting that primary tooth dentin is more reactive to acid conditioning. No difference was observed in the hybrid layers produced by the two adhesive systems (p = 0.7920). The increased thickness of the hybrid layer in primary teeth (25 to 30%) and the subsequent lack of complete penetration of adhesive resin into previously demineralized dentin may contribute to the lower bond strengths to primary dentin reported in the literature. If a narrower hybrid layer more uniformly infused with resin is the goal of dentin bonding, it is concluded that a differentiated protocol for bonding to primary dentin (with shorter time for dentin conditioning) can be used as a means to reproduce the hybrid layer thickness seen in permanent teeth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67017/2/10.1177_00220345960750061101.pd

The Influence of Repair Pathways on the Cytotoxicity and Mutagenicity Induced by the Pyridyloxobutylation Pathway of Tobacco-Specific Nitrosamines

Tobacco-specific nitrosamines, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN), are considered to be human carcinogens. Both compounds are metabolized to pyridyloxobutylating intermediates that react with DNA to form adducts such as 7-[4-(3-pyridyl)-4-oxobut-1-yl]-guanine (7-pobG), O2-[4-(3-pyridyl)-4-oxobut-1-yl]-cytosine (O2-pobC), O2-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxythymidine (O2-pobdT), O6-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxyguanosine (O6-pobdG) and 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing adducts. The role of specific DNA adducts in the overall genotoxic activity of the pyridyloxobutylation pathway is not known. One adduct, O6-pobdG, is mutagenic. To characterize the mutagenic and cytotoxic properties of pyridyloxobutyl DNA adducts, the impact of DNA repair pathways on the cytotoxic and mutagenic properties of the model pyridyloxobutylating agent, 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc) was investigated in Chinese hamster ovary (CHO) cell lines proficient or deficient in O6-alkylguanine DNA alkyltransferase (AGT), deficient in both AGT and base excision repair (BER), or deficient in both AGT and nucleotide excision repair (NER). The repair of the four pyridyloxobutyl DNA adducts was determined in the same cell lines via sensitive LC-MS/MS methods. NNKOAc was more cytotoxic in the cell lines lacking AGT, BER and NER repair pathways. It also induced more mutations in the hprt gene in the BER and NER deficient cell lines. However, AGT expression did not influence NNKOAc’s mutagenicity despite efficient repair of O6-pobdG. Analysis of the hprt mutational spectra indicated that NNKOAc primarily caused point mutations at AT base pairs. GC to AT transition mutations were a minor contributor to the overall mutation spectrum, providing a rationale for the observation that AGT does not protect against the overall mutagenic properties of NNKOAc in this model system. The only adduct affected by the absence of effective NER was O2-pobdT. Slower repair of O2-pobdT in NER deficient cells was associated with increased AT to TA transversion mutations, supporting the hypothesis that these mutations are caused by O2-pobdT. Together, these data support a hypothesis that the pyridyloxobutylation pathway generates multiple mutagenic and toxic adducts

Changing climate both increases and decreases European river floods

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere1. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe2. Any changes in river floods would have lasting implications for the design of flood protection measures and flood risk zoning. However, existing studies have been unable to identify a consistent continental-scale climatic-change signal in flood discharge observations in Europe3, because of the limited spatial coverage and number of hydrometric stations. Here we demonstrate clear regional patterns of both increases and decreases in observed river flood discharges in the past five decades in Europe, which are manifestations of a changing climate. Our results\u2014arising from the most complete database of European flooding so far\u2014suggest that: increasing autumn and winter rainfall has resulted in increasing floods in northwestern Europe; decreasing precipitation and increasing evaporation have led to decreasing floods in medium and large catchments in southern Europe; and decreasing snow cover and snowmelt, resulting from warmer temperatures, have led to decreasing floods in eastern Europe. Regional flood discharge trends in Europe range from an increase of about 11 per cent per decade to a decrease of 23 per cent. Notwithstanding the spatial and temporal heterogeneity of the observational record, the flood changes identified here are broadly consistent with climate model projections for the next century4,5, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management

Synthesis of thermoelectric magnesium-silicide pastes for 3D printing, electrospinning and low-pressure spray

In this work, eco-friendly magnesium-silicide (Mg2Si) semiconducting (n-type) thermoelectric pastes for building components concerning energy-harvesting devices through 3D printing, spray and electrospinning were synthetized and tested for the frst time. The Mg2Si fne powders were obtained through the combination of ball milling and thermal annealing under Ar atmosphere. While the latter process was crucial for obtaining the desired Mg2Si phase, the ball milling was indispensable for homogenizing and reducing the grain size of the powders. The synthetized Mg2Si powders exhibited a large Seebeck coeffcient of~487 µV/K and were blended with a polymeric solution in diferent mass ratios to adjust the paste viscosity to the diferent requirements of 3D printing, electrospinning and low-pressure spray. The materials produced in every single stage of the paste synthesis were characterized by a variety of techniques that unequivocally prove their viability for producing thermoelectric parts and components. These can certainly trigger further research and development in green thermoelectric generators (TEGs) capable of adopting any form or shape with enhanced thermoelectric properties. These green TEGs are meant to compete with common toxic materials such as Bi2Te3, PbTe and CoSb that have Seebeck coefcients in the range of ~ 290–700 μV/K, similar to that of the produced Mg2Si powders and lower than that of 3D printed bulk Mg2Si pieces, measured to be ~ 4866 μV/K. Also, their measured thermal conductivities proved to be signifcantly lower (~ 0.2 W/mK) than that reported for Mg2Si (≥4 W/mK). However, t is herein demonstrated that such thermoelectric properties are not stable over time. Pressureless sintering proved to be indispensable, but difcultly achievable by long thermal annealing (even above 32 h) in inert atmosphere at 400 °C, at least for bulk Mg2Si pieces constituted by a mean grain size of 2–3 μm. Hence, for overcoming this sintering challenge and become the silicide’s extrusion viable in the production of bulk thermoelectric parts, alternative pressureless sintering methods will have to be further explored

Global expansion of Mycobacterium tuberculosis lineage 4 shaped by colonial migration and local adaptation

On the basis of population genomic and phylogeographic analyses of 1669 Mycobacterium tuberculosis lineage 4 (L4) genomes, we find that dispersal of L4 has been completely dominated by historical migrations out of Europe. We demonstrate an intimate temporal relationship between European colonial expansion into Africa and the Americas and the spread of L4 tuberculosis (TB). Markedly, in the age of antibiotics, mutations conferring antimicrobial resistance overwhelmingly emerged locally (at the level of nations), with minimal cross-border transmission of resistance. The latter finding was found to reflect the relatively recent emergence of these mutations, as a similar degree of local restriction was observed for susceptible variants emerging on comparable time scales. The restricted international transmission of drug-resistant TB suggests that containment efforts at the level of individual countries could be successful

2020 WSES guidelines for the detection and management of bile duct injury during cholecystectomy.

Bile duct injury (BDI) is a dangerous complication of cholecystectomy, with significant postoperative sequelae for the patient in terms of morbidity, mortality, and long-term quality of life. BDIs have an estimated incidence of 0.4-1.5%, but considering the number of cholecystectomies performed worldwide, mostly by laparoscopy, surgeons must be prepared to manage this surgical challenge. Most BDIs are recognized either during the procedure or in the immediate postoperative period. However, some BDIs may be discovered later during the postoperative period, and this may translate to delayed or inappropriate treatments. Providing a specific diagnosis and a precise description of the BDI will expedite the decision-making process and increase the chance of treatment success. Subsequently, the choice and timing of the appropriate reconstructive strategy have a critical role in long-term prognosis. Currently, a wide spectrum of multidisciplinary interventions with different degrees of invasiveness is indicated for BDI management. These World Society of Emergency Surgery (WSES) guidelines have been produced following an exhaustive review of the current literature and an international expert panel discussion with the aim of providing evidence-based recommendations to facilitate and standardize the detection and management of BDIs during cholecystectomy. In particular, the 2020 WSES guidelines cover the following key aspects: (1) strategies to minimize the risk of BDI during cholecystectomy; (2) BDI rates in general surgery units and review of surgical practice; (3) how to classify, stage, and report BDI once detected; (4) how to manage an intraoperatively detected BDI; (5) indications for antibiotic treatment; (6) indications for clinical, biochemical, and imaging investigations for suspected BDI; and (7) how to manage a postoperatively detected BDI