Summary
The innate immune system is the primary defence against the versatile pathogen, Staphylococcus aureus. How this organism is able to avoid immune killing and cause infections is poorly ...understood. Using an established larval zebrafish infection model, we have shown that overwhelming infection is due to subversion of phagocytes by staphylococci, allowing bacteria to evade killing and found foci of disease. Larval zebrafish coinfected with two S. aureus strains carrying different fluorescent reporter gene fusions (but otherwise isogenic) had bacterial lesions, at the time of host death, containing predominantly one strain. Quantitative data using two marked strains revealed that the strain ratios, during overwhelming infection, were often skewed towards the extremes, with one strain predominating. Infection with passaged bacterial clones revealed the phenomenon not to bedue to adventitious mutations acquired by the pathogen. After infection of the host, all bacteria are internalized by phagocytes and the skewing of population ratios is absolutely dependent on the presence of phagocytes. Mathematical modelling of pathogen population dynamics revealed the data patterns are consistent with the hypothesis that a small number of infected phagocytes serve as an intracellular reservoir for S. aureus, which upon release leads to disseminated infection. Strategies to specifically alter neutrophil/macrophage numbers were used to map the potential subpopulation of phagocytes acting as a pathogen reservoir, revealing neutrophils as the likely ‘niche’. Subsequently in a murine sepsis model, S. aureus abscesses in kidneys were also found to be predominantly clonal, therefore likely founded by an individual cell, suggesting a potential mechanism analogous to the zebrafish model with few protected niches. These findings add credence to the argument that S. aureus control regimes should recognize both the intracellular as well as extracellular facets of the S. aureus life cycle.
In the search for new biological imaging agents, metal coordination compounds able to emit from triplet metal-to-ligand charge transfer (MLCT) states offer many advantages as luminescent probes of ...DNA structure. However, poor cellular uptake restricts their use in live cells. Here, we present a dinuclear ruthenium(II) polypyridyl system that works as a multifunctional biological imaging agent staining the DNA of eukaryotic and prokaryotic cells for both luminescence and transition electron microscopy. This MLCT 'light switch' complex directly images nuclear DNA of living cells without requiring prior membrane permeabilization. Furthermore, inhibition and transmission electron microscopy studies show this to be via a non-endocytotic, but temperature-dependent, mechanism of cellular uptake in MCF-7 cells, and confocal microscopy reveals multiple emission peaks that function as markers for cellular DNA structure.
Summary
In Bacillus subtilis, EzrA is involved in preventing aberrant formation of FtsZ rings and has also been implicated in the localization cycle of Pbp1. We have identified the orthologue of EzrA ...in Staphylococcus aureus to be essential for growth and cell division in this organism. Phenotypic analyses following titration of EzrA levels in S. aureus have shown that the protein is required for peptidoglycan synthesis as well as for assembly of the divisome at the midcell and cytokinesis. Protein interaction studies revealed that EzrA forms a complex with both the cytoplasmic components of the division machinery and those with periplasmic domains, suggesting that EzrA may be a scaffold molecule permitting the assembly of the division complex and forming an interface between the cytoplasmic cytoskeletal element FtsZ and the peptidoglycan biosynthetic apparatus active in the periplasm.
All life demands the temporal and spatial control of essential biological functions. In bacteria, the recent discovery of coordinating elements provides a framework to begin to explain cell growth ...and division. Here we present the discovery of a supramolecular structure in the membrane of the coccal bacterium Staphylococcus aureus, which leads to the formation of a large-scale pattern across the entire cell body; this has been unveiled by studying the distribution of essential proteins involved in lipid metabolism (PlsY and CdsA). The organization is found to require MreD, which determines morphology in rod-shaped cells. The distribution of protein complexes can be explained as a spontaneous pattern formation arising from the competition between the energy cost of bending that they impose on the membrane, their entropy of mixing, and the geometric constraints in the system. Our results provide evidence for the existence of a self-organized and nonpercolating molecular scaffold involving MreD as an organizer for optimal cell function and growth based on the intrinsic self-assembling properties of biological molecules.
This study evaluated the effects of natural extracts on chicken breast fillet marinades regarding the physicochemical properties, oxidative stability, and the Staphylococcus aureus and Escherichia ...coli inhibition during 21 days of storage. Chicken breast fillets (Pectoralis major) (128 units) purchased in a local market, were used, allocated in a completely randomized block design, in a 4 x 4 factorial scheme (antioxidant x storage time), totalling 16 treatments with eight replicates. The TBARS and the pH values were not influenced by the analyzed factors. For the color results, the values of L* and b* were lower in the marinated chicken breast fillets with basil and BHT, respectively. When assessing the effect of storage time, an increase in oxidation was observed up to 21 days of storage. For pH, a quadratic decrease after storage with an increase in the pH value from the 11th day of storage was observed. In the color results, there was a linear decrease in the L* value during the storage period and in the value of b* a quadratic effect was observed with a reduction of this intensity up to 21 days of storage. In relation to the value of a*, a quadratic effect with an increase in the red intensity from the 7 days of storage was observed. For the counting of the S. aureus, the treatments presented 102 CFU/g up to 14 days, except for the basil which exceeded the limit established by the legislation at 14 days.
RESUMO: O objetivo deste estudo foi avaliar os efeitos de extratos naturais em marinados de filés de peito de frango sobre as propriedades físico-químicas, estabilidade oxidativa e inibição Staphylococcus aureus e Escherichia coli durante 21 dias de armazenamento. Foram utilizados 128 filés de peito de frango (Pectoralis major) adquiridos no mercado local, alocados em delineamento de blocos inteiramente casualizados em fatorial 4 x 4 (antioxidante x tempo de armazenamento), totalizando 16 tratamentos com oito repetições. Os valores de TBARS e pH não foram influenciados pelos tratamentos. Para os resultados de cor apenas os valores de L* e b* foram influenciados pelos tratamentos, sendo os menores valores encontrados no tratamento com manjericão e BHT, respectivamente. Avaliando o efeito do tempo de armazenamento observou-se aumento da oxidação até 21 dias de estocagem. Para o pH verificou-se diminuição quadrática após a estocagem com aumento no valor do pH a partir do 11º dia de armazenamento. Nos resultados de cor, verificou-se queda linear no valor L* durante o período de armazenamento e no valor de b* observou-se efeito quadrático com redução dessa intensidade até 21 dias de estocagem. Em relação ao valor de a* observou-se efeito quadrático com aumento da intensidade a partir dos sete dias de armazenamento. Para contagem de S. aureus, os tratamentos apresentaram <102 UFC/g até 14 dias, exceto o manjericão que aos 14 dias excedeu o limite estabelecido pela legislação.
In recent years there has been an increasing problem with Staphylococcus aureus strains that are resistant to treatment with existing antibiotics. An important starting point for the development of ...new antimicrobial drugs is the identification of "essential" genes that are important for bacterial survival and growth.
We have developed a robust microarray and PCR-based method, Transposon-Mediated Differential Hybridisation (TMDH), that uses novel bioinformatics to identify transposon inserts in genome-wide libraries. Following a microarray-based screen, genes lacking transposon inserts are re-tested using a PCR and sequencing-based approach. We carried out a TMDH analysis of the S. aureus genome using a large random mariner transposon library of around a million mutants, and identified a total of 351 S. aureus genes important for survival and growth in culture. A comparison with the essential gene list experimentally derived for Bacillus subtilis highlighted interesting differences in both pathways and individual genes.
We have determined the first comprehensive list of S. aureus essential genes. This should act as a useful starting point for the identification of potential targets for novel antimicrobial compounds. The TMDH methodology we have developed is generic and could be applied to identify essential genes in other bacterial pathogens.
Summary
Bacterial cell division is a fundamental process that requires the coordinated actions of a number of proteins which form a complex macromolecular machine known as the divisome. The ...membrane‐spanning proteins DivIB and its orthologue FtsQ are crucial divisome components in Gram‐positive and Gram‐negative bacteria respectively. However, the role of almost all of the integral division proteins, including DivIB, still remains largely unknown. Here we show that the extracellular domain of DivIB is able to bind peptidoglycan and have mapped the binding to its β subdomain. Conditional mutational studies show that divIB is essential for Staphylococcus aureus growth, while phenotypic analyses following depletion of DivIB results in a block in the completion, but not initiation, of septum formation. Localisation studies suggest that DivIB only transiently localises to the division site and may mark previous sites of septation. We propose that DivIB is required for a molecular checkpoint during division to ensure the correct assembly of the divisome at midcell and to prevent hydrolytic growth of the cell in the absence of a completed septum.
Cardiac resynchronization therapy (CRT) has been established as an effective therapy for heart failure with reduced ejection fraction. Randomized clinical trials have shown its impact on mortality ...and HF hospitalizations, as well as improvement of symptoms and quality of life.
Finding clinical, electrocardiographic, and echocardiographic variables that may predict the response to cardiac resynchronization therapy (CRT).
We performed a single-center, observational, analytic, and retrospective study that included 102 patients with heart failure (HF) diagnosis who underwent CRT according to guideline-directed therapy from January 2010 to April 2020 in a third-level center. CRT response was defined as an improvement of New York Heart Association functional class in at least 1 category associated with a recovery of ≥ 5% in the left ventricular ejection fraction (LVEF).
Our study population was 102 patients of which 61 (59.8%) were men. The mean age at HF diagnosis was 54 ± 18.7 years. Ischemic heart disease was the etiology in 37 (36.3%) cases. Fifty-one (50%) patients were classified as responders. Responders had wider QRS, and lower LVEF and right ventricular fractional area change at baseline. After CRT, responders had a greater reduction of QRS duration, and improvement in LVEF, global longitudinal strain, and echocardiographic dyssynchrony parameters. Multivariate regression analysis showed that left bundle branch block (LBBB), left ventricular end-diastolic volume (LVEDV), tricuspid annular plane systolic excursion (TAPSE), and baseline difference of pre-ejection periods were predictors of a positive response to CRT in this population.
LBBB, TAPSE, LVEDV, and pre-ejection time difference are independent variables that can predict adequate response to CRT.
Tuberculum sellae meningiomas (TSM) account for 3–10% of intracranial meningiomas. Visual loss is the presenting symptom in up to 80% of cases. Surgical management poses a great challenge due to ...tumor proximity to neurovascular structures such as the optic nerve and the internal carotid artery (ICA); hence, there is controversy regarding the optimal approach. The aim of this study is to determine differences in visual outcomes between transcranial (TCA) and endoscopic endonasal (EEA) approaches.
A retrospective study including 29 patients with TSM surgically treated by TCA or EEA between 2011 and 2023 in a single referral center was conducted. Pre-and post-operative neuro-ophthalmologic evaluations, focusing on visual acuity and campimetry, were evaluated.
Sixteen (55.16%) patients were intervened through a TCA and the remaining 13 (44.84%) via an EEA. The lesions in each group were similar in terms of pre- operative volume (15.12 vs 12.9 cm3, p = 0.497) and neurovascular invasion (optic canal invasion 48.26 vs 41.37%, p = 0.664; ICA 44.81 vs 31.03%, p = 0.797). There were no significant differences in visual outcomes between both approaches; TCA presented an improvement of 5.18 points in visual fields (p = 0.140), whereas EEA had an improvement of 17.39 points in visual acuity (p = 0.114).
EEA seems to offer greater improvement in visual acuity than TCA. However, the ideal approach should be individualized; taking into account the tumor’s volume and invasiveness, as well as the patient's visual complaints.
Background
The shipping industry has grown spectacularly during the last 50 years transporting nowadays, approximately, the 80–90% of goods worldwide. However, maritime transport remains a highly ...inefficient industry. Only in the last 10–15 years has the industry started studying how to optimize navigation speeds and digitization is just entering ports. Consequently, institutions like the International Maritime Organization (IMO) are pressing towards the adoption of measures that increase the industry efficiency, like Just-In-Time (JIT) operations.
Methods and Results
This paper shows why the Sea Traffic Management (STM) concept, based on stakeholder collaboration, is a JIT enabler. To do so, we analyze 1 year of navigation data of 33 ships, estimating the impact of JIT barriers on shipping and showing the benefits that the adoption of STM, with different maturity levels, could provide to the industry. Our evaluation shows that, only for containerships, STM can help reducing by 15–23% of fuel consumption and GHG emissions.
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