Abstract
While the major virulence factors for
Vibrio cholerae
, the cause of the devastating diarrheal disease cholera, have been extensively studied, the initial intestinal colonization of the ...bacterium is not well understood because non-human adult animals are refractory to its colonization. Recent studies suggest the involvement of an interbacterial killing device known as the type VI secretion system (T6SS). Here, we tested the T6SS-dependent interaction of
V. cholerae
with a selection of human gut commensal isolates. We show that the pathogen efficiently depleted representative genera of the Proteobacteria in vitro, while members of the
Enterobacter cloacae
complex and several
Klebsiella
species remained unaffected. We demonstrate that this resistance against T6SS assaults was mediated by the production of superior T6SS machinery or a barrier exerted by group I capsules. Collectively, our data provide new insights into immunity protein-independent T6SS resistance employed by the human microbiota and colonization resistance in general.
Edible films and coatings are thin layers, with a thickness of generally less than 0.3 mm, that are used for centuries to protect food products and to avoid the deterioration of their ingredients. ...While an edible coating is formed directly on the food surface by spraying, dipping or spreading techniques, an edible film is first produced by solvent casting, compression moulding or extrusion procedures and posteriorly implemented into the food products, being placed on or between food components. The food sector is the main consumer of packaging materials, with the edible films and coatings being mainly applied into meat and seafood, fruits and vegetables and dairy products. These packaging materials, normally formed by a cohesive structured biopolymer, additives and/or a solvent, can also be used as carriers of several active ingredients, like colourants, flavours, nutrients and antimicrobial and antioxidant compounds, which can prolong the shelf life, improve the organoleptic characteristics and enhance the nutritional value of the final product. Nowadays, due to health and environmental concerns, the use of natural antioxidant and antimicrobial sources, like natural extracts, is emerging in the packaging research sector, being widely applied as active ingredients in edible film and coating formulations. A wide range of studies revealed the comprehensive interests in edible films and coatings with functional properties. So, the main objective of this review is to cover the recent works on edible films and coatings, including the investigation of recent advances in the incorporation of active compounds, namely natural extracts, and the challenges and opportunities for future research.
Background and purpose
The aim was to evaluate the efficacy of the catechol‐O‐methyltransferase inhibitor opicapone (25 and 50 mg) as adjunct therapy to levodopa in a pooled population of Parkinson's ...disease patients who participated in the pivotal double‐blind trials of opicapone and their 1‐year open‐label extensions.
Methods
Data (placebo, opicapone 25 mg and opicapone 50 mg) from the BIPARK‐1 and BIPARK‐2 double‐blind and open‐label studies were combined. The studies had similar designs, eligibility criteria and assessment methods. The primary efficacy variable in both double‐blind studies was the change from baseline in absolute OFF time based on patient diaries.
Results
Double‐blind treatment with opicapone (25 and 50 mg) significantly reduced absolute daily OFF time from a baseline of 6.1–6.6 h. The mean (and 95% confidence interval) treatment effect versus placebo was −35.1 (−62.1, −8.2) min (P = 0.0106) for the 25 mg dose and −58.1 (−84.5, −31.7) min (P < 0.0001) for the 50 mg dose. Reductions in OFF time were mirrored by significant increases in ON time without troublesome dyskinesia (P < 0.05 and P < 0.0001 for the 25 and 50 mg doses, respectively). No significant differences were observed for ON time with troublesome dyskinesia. Patient diary results from the open‐label phase indicated a maintenance of effect for patients previously treated with opicapone 50 mg. The group previously treated with the 25 mg dose benefitted with further optimization of therapy during the open‐label phase, whilst switching from placebo to opicapone led to significant reductions in OFF time and increased ON time.
Conclusions
Over at least 1 year of open‐label therapy, opicapone consistently reduced OFF time and increased ON time without increasing the frequency of troublesome dyskinesia.
Recently, the missing link between homogeneous and heterogeneous catalysis has been found and it was named single-atom catalysis (SAC). However, the SAC field still faces important challenges, one of ...which is controlling the bonding/coordination between the single atoms and the support in order to compensate for the increase in surface energy when the particle size is reduced due to atomic dispersion. Excellent candidates to meet this requirement are carbon nitride (CN)-based materials. Metal atoms can be firmly trapped in nitrogen-rich coordination sites in CN materials, which makes them a unique class of hosts for preparing single-atom catalysts (SACs). As one of the most promising two-dimensional supports to stabilize isolated metal atoms, CN materials have been increasingly employed for preparing SACs. Herein, we will cover the most recent advances in single-atoms supported by CN materials. In this review, the most important characterization techniques and the challenges faced in this topic will be discussed, and the commonly employed synthetic methods will be delineated for different CN materials. Finally, the catalytic performance of SACs based on carbon nitrides will be reviewed with a special focus on their photocatalytic applications. In particular, we will prove CN as a non-innocent support. The relationship between single-atoms and carbon nitride supports is two-way, where the single-atoms can change the electronic properties of the CN support, while the electronic features of the CN matrix can tune the catalytic activity of the single sites in photocatalytic reactions. Finally, we highlight the frontiers in the field, including analytical method development, truly controlled synthetic methods, allowing the fine control of loading and multi-element synthesis, and how understanding the two-way exchange behind single-atoms and CN supports can push this topic to the next level.
Carbon nitride single-atom based catalysts: supporting the transition from the fossil past to the green future.
This work investigates the effect of clinoptilolite, a natural zeolite, as filler on the mechanical performance and heavy metal's adsorption capacity of the metakaolin-based geopolymers. ...Clinoptilolite was chosen as an inexpensive additive with high adsorption capacity, replacing metakaolin (0, 25, 50 and 75%) in the synthesis of four different geopolymers (MK100, MK75, MK50 and MK25, respectively). To produce geopolymers with low environmental impact, during the geopolymerization processes the SiO2/Al2O3 and Na2O/Al2O3 molar ratios were kept constant at 1, to reduce sodium silicate and sodium hydroxide to a minimum. The final products were studied by powder X-ray diffraction, 27Al and 29Si solid-state NMR and Scanning electron microscopy. Moreover, strength parameters and heavy metals Pb2+, Zn2+, Cu2+, Cd2+ and Cr3+ adsorption tests were performed. The results show that geopolymerization in the presence of zeolite leads to an increase of the compressive strength of all blended geopolymers, with an optimal metakaolin precursor/zeolite filler ratio of 50:50, affording the highest strength (8.8MPa at 28days). The adsorption of metal cations on geopolymers was well fitted using the Langmuir model (0.97<R2<0.99). The geopolymers adsorbed heavy metals in the order Pb2+>Cd2+>Zn2+, Cu2+>Cr3+. The maximum adsorption capacity of Cu2+ and Cr3+ was highest for geopolymer with 100% of metakaolin (MK100), while for Pb2+, Cd2+ and Zn2+ the highest adsorption capacity is for geopolymers with 75% of metakaolin (MK75), indicating that 25% zeolite addition to geopolymers has efficiently improved the adsorption capacity.
•Natural zeolite was chosen as filler in metakaolin based geopolymers.•Geopolymer with 50% of zeolite addition shows the highest compressive strength.•Geopolymers adsorb heavy metals in the order Pb2+>Cd2+>Zn2+, Cu2+>Cr3+.
To review articles reporting on the development of soluble biomarkers in osteoarthritis (OA) over the past year.
Two literature searches were conducted using the PubMed database for articles ...published between April 1, 2021 and March 31, 2022. Two searches were done, one on soluble biomarkers and another on circulating non-coding RNAs in OA. Additional articles were hand-picked to highlight emerging biomarker trends in OA.
Of 348 publications retrieved, we included 20 articles with 3 that were hand-picked for the narrative synthesis. We review recent data on soluble biomarkers and circulating non-coding microRNAs in OA using the BIPED classification system. We highlight studies using proteomics to show that cartilage acidic protein 1 (CRTAC1) is a promising biomarker, helping diagnose and estimate severity in hand, hip, and knee OA. Subtle changes in the structure of glycosaminoglycans from the extracellular cartilage matrix were shown to discriminate OA from non-OA cartilage. C-reactive protein metabolite (CRPM) and collagen metabolites may help discriminate subsets of OA patients as well as disease progression. Additionally, physical activity may impact determination of biomarkers. We also report on circulating microRNAs, lncRNAs, and circRNAs in OA and their predictive accuracy in diagnosis and prognosis.
Biomarkers for routine use are still an unmet need in the OA clinical scenario. Emerging data and novel classes of biomarkers (i.e., non-coding RNAs) show promise. Although still requiring validation in multiple independent cohorts, the past year brought advances towards a ready-to-use, reproducible, cost-effective biomarker, namely CRTAC1, to better manage the OA patient.
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•Systematic study of protein phase behaviour in a droplet-based microreactor.•Numerical prediction of droplet sizes in a flow-focusing geometry.•Parametric study to quantify the ...influence of the droplet volume on nucleation.•Parametric study of the influence of the droplet volume on the phase diagram limits.
This work reports a cheap and easy-to-use droplet-based microfluidic platform for the study of protein crystallization, offering the possibility to characterize the protein phase behaviour, and the effect of volumetric and interfacial phenomena on the crystallization mechanism. We conducted a parametric study supported by comparison with literature data, to quantify the influence of the droplet volume on the thermodynamic (solubility data) and kinetic (metastability data) parameters, using lysozyme as a model protein. Experiments were performed in a tubular microreactor at low Capillary numbers (4.1 × 10−5–2.3 × 10−4), resulting in a broad range of droplet sizes. The droplet formation in a flow-focusing geometry was also numerically studied using CFD and a correlation for the droplet size was developed. Subsequently, the lysozyme phase behaviour and the possible mechanisms associated with the nucleation process were evaluated. While crystallization in small volume droplets is usually characterized by a low nucleation probability and correspondingly low number of crystals, we did not observe this in our experiments. A potential explanation for this is the complex and stochastic mechanism of nucleation, including the competition between monomers and oligomers in solution.
The physical and chemical characteristics of peat were assessed through measurement of pH, percentage of organic matter, cationic exchange capacity (CEC), elemental analysis, infrared spectroscopy ...and quantitative analysis of metals by ICP OES. Despite the material showed to be very acid in view of the percentage of organic matter, its CEC was significant, showing potential for retention of metal ions. This characteristic was exploited by coupling a peat mini-column to a flow system based on the multicommutation approach for the in-line copper concentration prior to flame atomic absorption spectrometric determination. Cu(II) ions were adsorbed at pH 4.5 and eluted with 0.50
mol
L
−1 HNO
3. The influence of chemical and hydrodynamic parameters, such as sample pH, buffer concentration, eluent type and concentration, sample flow-rate and preconcentration time were investigated. Under the optimized conditions, a linear response was observed between 16 and 100
μg
L
−1, with a detection limit estimated as 3
μg
L
−1 at the 99.7% confidence level and an enrichment factor of 16. The relative standard deviation was estimated as 3.3% (
n
=
20). The mini-column was used for at least 100 sampling cycles without significant variation in the analytical response. Recoveries from copper spiked to lake water or groundwater as well as concentrates used in hemodialysis were in the 97.3–111% range. The results obtained for copper determination in these samples agreed with those achieved by graphite furnace atomic absorption spectrometry (GFAAS) at the 95% confidence level.
Nowadays, diseases like cancer, Alzheimer and Parkinson are becoming more common, being a result of an uncontrolled production of free radicals and an unbalanced mechanism of antioxidant protection. ...In this context, antioxidants compounds emerge as effective and continuous prevention agents of the above-mentioned diseases. The most available and soft antioxidant substances are the natural ones, like the polyphenols, that can be found in some everyday foods. However, the consumption of this type of products do not provide the necessary antioxidants amount and, for that reason, the production of functional products, incorporated with natural antioxidant compounds, has become more relevant.
Several limitations have been associated with the use of these substances, due to their high probability of being degraded if exposed to adverse conditions. A viable solution is the use of microencapsulation techniques, which allow the protection of the biochemical functionalities of a wide range of compounds, by their incorporation into a protective matrix.
The main purpose of the current work is to focus on important topics about the microencapsulation of polyphenols, studying the specific case of the Sambucus Nigra L. extracts, including the description of the most important extraction methods for plant samples and of the encapsulation techniques and wall materials used to encapsulate polyphenols. It was also made an approach to the release tests involved in the release phenomenon of the bioactive compounds from the natural resources, including its mechanisms, simulated release media and kinetics.
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•Polyphenols allows an effective and continuous prevention of several diseases.•Sambucus Nigra L. is rich in polyphenols, that exhibit antioxidant properties.•Sambucus Nigra L. is available in several regions of the globe.•Polyphenols are useful for food, pharmaceutic and cosmetic applications.•Microencapsulation may promote the stabilization of polyphenols.
Despite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction ...system VarS/VarA is not well understood. This pathway, which mainly signals through the downstream protein CsrA, is highly conserved among gamma-proteobacteria, indicating there is likely a broader function of this system beyond virulence regulation. In this study, we investigated the VarA-CsrA signaling pathway and discovered a previously unrecognized link to the shape of the bacterium. We observed that varA-deficient V. cholerae cells showed an abnormal spherical morphology during late-stage growth. Through peptidoglycan (PG) composition analyses, we discovered that these mutant bacteria contained an increased content of disaccharide dipeptides and reduced peptide crosslinks, consistent with the atypical cellular shape. The spherical shape correlated with the CsrA-dependent overproduction of aspartate ammonia lyase (AspA) in varA mutant cells, which likely depleted the cellular aspartate pool; therefore, the synthesis of the PG precursor amino acid meso-diaminopimelic acid was impaired. Importantly, this phenotype, and the overall cell rounding, could be prevented by means of cell wall recycling. Collectively, our data provide new insights into how V. cholerae use the VarA-CsrA signaling system to adjust its morphology upon unidentified external cues in its environment.
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