The effect of SARS-CoV-2 variants on the plasma oxylipins and PUFAs of COVID-19 patients

Oxylipins are important signalling compounds that are significantly involved in the regulation of the immune system and the resolution of inflammation. Lipid metabolism is strongly activated upon SARS-CoV-2 infection, however the modulating effects of oxylipins induced by different variants remain unexplored. Here, we compare the plasma profiles of thirty-seven oxylipins and four PUFAs in subjects infected with Wild-type, Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (B.1.1.529) variants. The results suggest that oxidative stress and inflammation resulting from COVID-19 were highly dependent on the SARS-CoV-2 variant, and that the Wild-type elicited the strongest inflammatory storm. The Alpha and Delta variants induced a comparable lipid profile alteration upon infection, which differed significantly from Omicron. The latter variant increased the levels of pro-inflammatory mediators and decreased the levels of omega-3 PUFA in infected patients. We speculate that changes in therapeutics, vaccination, and prior infections may have a role in the alteration of the oxylipin profile besides viral mutations. The results shed new light on the evolution of the inflammatory response in COVID-19.

Biosensing systems for the detection and quantification of methane gas

Climate change due to the continuous increase in the release of green-house gasses associated with anthropogenic activity has made a significant impact on the sustainability of life on our planet. Methane (CH4) is a green-house gas whose concentrations in the atmosphere are on the rise. CH4 measurement is important for both the environment and the safety at the industrial and household level. Methanotrophs are distinguished for their unique characteristic of using CH4 as the sole source of carbon and energy, due to the presence of the methane monooxygenases that oxidize CH4 under ambient temperature conditions. This has attracted interest in the use of methanotrophs in biotechnological applications as well as in the development of biosensing systems for CH4 quantification and monitoring. Biosensing systems using methanotrophs rely on the use of whole microbial cells that oxidize CH4 in presence of O2, so that the CH4 concentration is determined in an indirect manner by measuring the decrease of O2 level in the system. Although several biological properties of methanotrophic microorganisms still need to be characterized, different studies have demonstrated the feasibility of the use of methanotrophs in CH4 measurement. This review summarizes the contributions in methane biosensing systems and presents a prospective of the valid use of methanotrophs in this field. KEY POINTS: • Methanotroph environmental relevance in methane oxidation • Methanotroph biotechnological application in the field of biosensing • Methane monooxygenase as a feasible biorecognition element in biosensors.

Salivary lipid mediators: Key indexes of inflammation regulation in heart failure disease

Cardiovascular diseases (CVDs) are the leading cause of premature death and disability in humans and their incidence continues to increase. Oxidative stress and inflammation have been recognized as key pathophysiological factors in cardiovascular events. The targeted modulation of the endogenous mechanisms of inflammation, rather than its simple suppression, will become key in treating chronic inflammatory diseases. A comprehensive characterization of the signalling molecules involved in inflammation, such as endogenous lipid mediators, is thus needed. Here, we propose a powerful MS-based platform for the simultaneous quantitation of sixty salivary lipid mediators in CVD samples. Saliva, which represents a non-invasive and painless alternative to blood, was collected from patients suffering from acute and chronic heart failure (AHF and CHF, respectively), obesity and hypertension. Of all the patients, those with AHF and hypertension showed higher levels of isoprostanoids, which are key indexes of oxidant insult. Compared to the obese population, AHF patients showed lower levels (p < 0.02) of antioxidant omega-3 fatty acids, in line with the "malnutrition-inflammation complex syndrome" typical of HF patients. At hospital admission, AHF patients showed significantly higher levels (p < 0.001) of omega-3 DPA and lower levels (p < 0.04) of lipoxin B₄ than CHF patients, suggesting a lipid rearrangement typical of the failing heart during acute decompensation. If confirmed, our results highlight the potential use of lipid mediators as predictive markers of re-acutisation episodes, thus providing opportunities for preventive intervention and a reduction in hospitalizations.

3D Printed Platform for Impedimetric Sensing of Liquids and Microfluidic Channels

Fused deposition modeling 3D printing (FDM-3DP) employing electrically conductive filaments has recently been recognized as an exceptionally attractive tool for the manufacture of sensing devices. However, capabilities of 3DP electrodes to measure electric properties of materials have not yet been explored. To bridge this gap, we employ bimaterial FDM-3DP combining electrically conductive and insulating filaments to build an integrated platform for sensing conductivity and permittivity of liquids by impedance measurements. The functionality of the device is demonstrated by measuring conductivity of aqueous potassium chloride solution and bottled water samples and permittivity of water, ethanol, and their mixtures. We further implement an original idea of applying impedance measurements to investigate dimensions of 3DP channels as base structures of microfluidic devices, complemented by their optical microscopic analysis. We demonstrate that FDM-3DP allows the manufacture of microchannels of width down to 80 μm.

Sweat analysis with a wearable sensing platform based on laser-induced graphene

The scientific community has shown increasing interest in laser scribing for the direct fabrication of conductive graphene-based tracks on different substrates. This can enable novel routes for the noninvasive analysis of biofluids (such as sweat or other noninvasive matrices), whose results can provide the rapid evaluation of a person's health status. Here, we present a wearable sensing platform based on laser induced graphene (LIG) porous electrodes scribed on a flexible polyimide sheet, which samples sweat through a paper sampler. The device is fully laser manufactured and features a two layer design with LIG-based vertical interconnect accesses. A detailed characterization of the LIG electrodes including pore size, surface groups, surface area in comparison to electroactive surface area, and the reduction behavior of different LIG types was performed. The bare LIG electrodes can detect the electrochemical oxidation of both uric acid and tyrosine. Further modification of the surface of the LIG working electrode with an indoaniline derivative [4-((4-aminophenyl)imino)-2,6-dimethoxycyclohexa-2,5-dien-1-one] enables the voltammetric measurement of pH with an almost ideal sensitivity and without interference from other analytes. Finally, electrochemical impedance spectroscopy was used to measure the concentrations of ions through the analysis of the sweat impedance. The device was successfully tested in a real case scenario, worn on the skin during a sports session. In vitro tests proved the non-cytotoxic effect of the device on the A549 cell line.

MS-based targeted profiling of oxylipins in COVID-19: A new insight into inflammation regulation

The key role of inflammation in COVID-19 induced many authors to study the cytokine storm, whereas the role of other inflammatory mediators such as oxylipins is still poorly understood. IMPRECOVID was a monocentric retrospective observational pilot study with COVID-19 related pneumonia patients (n = 52) admitted to Pisa University Hospital between March and April 2020. Our MS-based analytical platform permitted the simultaneous determination of sixty plasma oxylipins in a single run at ppt levels for a comprehensive characterisation of the inflammatory cascade in COVID-19 patients. The datasets containing oxylipin and cytokine plasma levels were analysed by principal component analysis (PCA), computation of Fisher's canonical variable, and a multivariate receiver operating characteristic (ROC) curve. Differently from cytokines, the panel of oxylipins clearly differentiated samples collected in COVID-19 wards (n = 43) and Intensive Care Units (ICUs) (n = 27), as shown by the PCA and the multivariate ROC curve with a resulting AUC equal to 0.92. ICU patients showed lower (down to two orders of magnitude) plasma concentrations of anti-inflammatory and pro-resolving lipid mediators, suggesting an impaired inflammation response as part of a prolonged and unsolvable pro-inflammatory status. In conclusion, our targeted oxylipidomics platform helped shedding new light in this field. Targeting the lipid mediator class switching is extremely important for a timely picture of a patient's ability to respond to the viral attack. A prediction model exploiting selected lipid mediators as biomarkers seems to have good chances to classify patients at risk of severe COVID-19.

A label-free impedance biosensing assay based on CRISPR/Cas12a collateral activity for bacterial DNA detection

The rapid and selective identification in the clinical setting of pathogenic bacteria causing healthcare associated infections (HAIs) and in particular blood stream infections (BSIs) is a major challenge, as the number of people affected worldwide and the associated mortality are on the rise. In fact, traditional laboratory techniques such culture and polymerase chain reaction (PCR)-based methodologies are often associated to long turnaround times, which justify the pressing need for the development of rapid, specific and portable point of care devices. The recently discovered clustered regularly interspaced short palindromic repeat loci (CRISPR) and the new class of programmable endonuclease enzymes called CRISPR associated proteins (Cas) have revolutionised molecular diagnostics. The use of Cas proteins in optical and electrochemical biosensing devices has significantly improved the detection of nucleic acids in clinical samples. In this study, a CRISPR/Cas12a system was coupled with electrochemical impedance spectroscopy (EIS) measurements to develop a label-free biosensing assay for the detection of Escherichia coli and Staphylococcus aureus, two bacterial species commonly associated to BSI infections. The programmable Cas12a endonuclease activity, induced by a specific guide RNA (gRNA), and the triggered collateral activity were assessed in in vitro restriction analyses, and evaluated thanks to impedance measurements using a modified gold electrode. The Cas12a/gRNA system was able to specifically recognize amplicons from different clinical isolates of E. coli and S. aureus with a limit of detection of 3 nM and a short turnaround time approximately of 1.5 h. To the best of our knowledge, this is the first biosensing device based on CRISPR/Cas12a label free impedance assay.

Biphenyl substituted lysine derivatives as recognition elements for the matrix metalloproteinases MMP-2 and MMP-9

Matrix metalloproteinases (MMPs) are an important factor in cancer progression and metastasis, especially gelatinases MMP-2 and MMP-9. A simple methodology for their detection and monitoring is highly desirable. Molecular probes have been very widely and successfully applied to study the activity of MMPs in cellular processes in vitro. We thus synthesized a small compound library of MMP-2 and MMP-9 binding probes based on drug molecules and endowed with free amine groups for the functionalization of transducer surfaces. In this study, we combined experimental results obtained by a kinetic fluorogenic peptide substrate cleavage assay with molecular modeling studies in order to assess the ability of the probe to bind to their target enzymes. The synthesized biphenyl substituted lysine derivatives showed IC₅₀-values in the low nanomolar concentration range against MMP-2 (ligands 3a-d: 3 nM to 8 µM, ligands 4a-d: 45 nM to 350 µM) and low micromolar range against MMP-9 (ligands 3a-d: 350 nM to 60 µM, ligands 4a-d: 5 µM to 600 µM), with a selectivity up to more than 160-fold for MMP-2. The experimental results correlated well with molecular modelling with FleXAID and X-score functions. We showed that in our compound series, the side chain remained far away from the S1' cavity and the ligand for all the docked minima. Ligands 4a-d with their free amine group on the side chain may thus be bound to transducer surfaces for the fabrication of sensors, while retaining their activity against their target enzymes.

Stability of volatile organic compounds in sorbent tubes following SARS-CoV-2 inactivation procedures

COVID-19 is a highly transmissible respiratory illness that has rapidly spread all over the world causing more than 115 million cases and 2.5 million deaths. Most epidemiological projections estimate that the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus causing the infection will circulate in the next few years and raise enormous economic and social issues. COVID-19 has a dramatic impact on health care systems and patient management, and is delaying or stopping breath research activities due to the risk of infection to the operators following contact with patients, potentially infected samples or contaminated equipment. In this scenario, we investigated whether virus inactivation procedures, based on a thermal treatment (60 °C for 1 h) or storage of tubes at room temperature for 72 h, could be used to allow the routine breath analysis workflow to carry on with an optimal level of safety during the pandemic. Tests were carried out using dry and humid gaseous samples containing about 100 representative chemicals found in exhaled breath and ambient air. Samples were collected in commercially available sorbent tubes, i.e. Tenax GR and a combination of Tenax TA, Carbograph 1TD and Carboxen 1003. Our results showed that all compounds were stable at room temperature up to 72 h and that sample humidity was the key factor affecting the stability of the compounds upon thermal treatment. Tenax GR-based sorbent tubes were less impacted by the thermal treatment, showing variations in the range 20%-30% for most target analytes. A significant loss of aldehydes and sulphur compounds was observed using carbon molecular sieve-based tubes. In this case, a dry purge step before inactivation at 60 °C significantly reduced the loss of the target analytes, whose variations were comparable to the method variability. Finally, a breath analysis workflow including a SARS-CoV-2 inactivation treatment is proposed.

Advances in biosensing: The CRISPR/Cas system as a new powerful tool for the detection of nucleic acids

A main challenge in the development of biosensing devices for the identification and quantification of nucleic acids is to avoid the amplification of the genetic material from the sample by polymerase chain reaction (PCR), which is at present necessary to enhance sensitivity and selectivity of assays. PCR has undoubtedly revolutionized genetic analyses, but it requires careful purification procedures that are not easily implemented in point of care (POC) devices. In recent years, a new strategy for nucleic acid detection based on clustered regularly interspaced short palindromic repeats (CRISPR) and associated protein systems (Cas) seems to offer unprecedented possibilities. The coupling of the CRISPR/Cas system with recent isothermal amplification methods is fostering the development of innovative optical and electrochemical POC devices. In this review, the mechanisms of action of several new CRISRP/Cas systems are reported together with their use in biosensing of nucleic acids.

The development of a fully integrated 3D printed electrochemical platform and its application to investigate the chemical reaction between carbon dioxide and hydrazine

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An integrated electrochemical platform was manufactured by bi-material 3D printing.

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It was applied to investigate the reaction between hydrazine and carbon dioxide.

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Experimental results were supported by finite-element method numerical simulations.

The combination of computer assisted design and 3D printing has recently enabled fast and inexpensive manufacture of customized ‘reactionware’ for broad range of electrochemical applications. In this work bi-material fused deposition modeling 3D printing is utilized to construct an integrated platform based on a polyamide electrochemical cell and electrodes manufactured from a polylactic acid-carbon nanotube conductive composite. The cell contains separated compartments for the reference and counter electrode and enables reactants to be introduced and inspected under oxygen-free conditions. The developed platform was employed in a study investigating the electrochemical oxidation of aqueous hydrazine coupled to its bulk reaction with carbon dioxide. The analysis of cyclic voltammograms obtained in reaction mixtures with systematically varied composition confirmed that the reaction between hydrazine and carbon dioxide follows 1/1 stoichiometry and the corresponding equilibrium constant amounts to (2.8 ± 0.6) × 10³. Experimental characteristics were verified by results of numerical simulations based on the finite-element-method.

A graphene-based pH sensor on paper for human plasma and seawater

The relevance of pH assessment in clinical analysis, environmental and industrial control, has raised the demand for the development of portable, low cost and easy-to-use monitoring systems. This paper proposes a pH sensor printed on a paper support passivated with a solid-ink coating. The sensor exploits the pH sensitivity of a reduced graphene oxide functionalized with 3-(4-aminophenil)propionic acid. The sensor responded in the pH range [4], [10] and had a sensitivity of 46 mV/pH. Tests on human plasma and seawater proved this pH sensor to have similar performances than those of a commercial pH-meter with an uncertainty of 0.1 and 0.2 pH unit in plasma and seawater, respectively.

A Biosensor for the Detection of Acetylcholine and Diazinon

Acetylcholine is a neurotransmitter and a neuromodulator found in the autonomic, peripheral and central nervous systems. Diazinon is a pesticide with toxic effects on humans, such as the inhibition of acetylcholine. In this paper, a biosensor is proposed for the detection of acetylcholine (range 70 - 1000 μM) and diazinon (range 0.3 - 20000 ppb). This biosensor combines a pH-sensitive layer of reduced graphene oxide functionalized with 4-aminobenzoic acid and acetylcholinesterase. This enzyme was immobilized on reduced graphene oxide and it catalyzed the conversion of acetylcholine into choline and acetic acid, locally decreasing the pH value and triggering the sensor response. The limit of detection for the acetylcholine and diazinon were 70 μM and 0.3 ppb, respectively.

Renormalizable two-parameter piecewise isometries

We exhibit two distinct renormalization scenarios for two-parameter piecewise isometries, based on 2π/5 rotations of a rhombus and parameter-dependent translations. Both scenarios rely on the recently established renormalizability of a one-parameter triangle map, which takes place if and only if the parameter belongs to the algebraic number field K=Q(5) associated with the rotation matrix. With two parameters, features emerge which have no counterpart in the single-parameter model. In the first scenario, we show that renormalizability is no longer rigid: whereas one of the two parameters is restricted to K, the second parameter can vary continuously over a real interval without destroying self-similarity. The mechanism involves neighbouring atoms which recombine after traversing distinct return paths. We show that this phenomenon also occurs in the simpler context of Rauzy-Veech renormalization of interval exchange transformations, here regarded as parametric piecewise isometries on a real interval. We explore this analogy in some detail. In the second scenario, which involves two-parameter deformations of a three-parameter rhombus map, we exhibit a weak form of rigidity. The phase space splits into several (non-convex) invariant components, on each of which the renormalization still has a free parameter. However, the foliations of the different components are transversal in parameter space; as a result, simultaneous self-similarity of the component maps requires that both of the original parameters belong to the field K.

Flights in a pseudo-chaotic system

We consider the problem of transport in a one-parameter family of piecewise rotations of the torus, for rotation number approaching 1∕4. This is a zero-entropy system which in this limit exhibits a divided phase space, with island chains immersed in a "pseudo-chaotic" region. We identify a novel mechanism for long-range transport, namely the adiabatic destruction of accelerator-mode islands. This process originates from the approximate translational invariance of the phase space and leads to long flights of linear motion, for a significant measure of initial conditions. We show that the asymptotic probability distribution of the flight lengths is determined by the geometric properties of a partition of the accelerator-mode island associated with the flight. We establish the existence of flights travelling distances of order O(1) in phase space. We provide evidence for the existence of a scattering process that connects flights travelling in opposite directions.

[How to control postoperative pain: intravenous route]

Intravenous administration of analgesic drugs is one of the most common ways to control post-operative pain. It can be used in almost all kinds of surgical interventions and particularly those of medium and high complexity. Besides, when other techniques are contraindicated because of clinical and/or managing problems, intravenous way finds its best application. Among analgesic drugs NSAID (ketorolac) and opioids (tramadol, morphine, buprenorphine) are most frequently used. As to administration techniques, elastomeric pump is, according to personal experience, a simple-to-manage, practical and precise device with lower cost respect to other administration set. Elastomeric pump is a single use reservoir that allows continuous administration of drugs with a uniform pre-set infusion speed. Finally, guide-lines, showing pre-load and infusion doses of analgesic drugs, based on pain intensity, are presented.

Arithmetical method to detect integrability in maps

We develop a method to detect the presence of integrals of the motion in symplectic rational maps, by representing these maps over finite fields and examining their orbit structure. We find markedly different orbit statistics depending upon whether the map is integrable or not.

Complexity of regular invertible p-adic motions

We consider issues of computational complexity that arise in the study of quasi-periodic motions (Siegel discs) over the p-adic integers, where p is a prime number. These systems generate regular invertible dynamics over the integers modulo p(k), for all k, and the main questions concern the computation of periods and orbit structure. For a specific family of polynomial maps, we identify conditions under which the cycle structure is determined solely by the number of Siegel discs and two integer parameters for each disc. We conjecture the minimal parametrization needed to achieve-for every odd prime p-a two-disc tessellation with maximal cycle length. We discuss the relevance of Cebotarev's density theorem to the probabilistic description of these dynamical systems. (c) 2001 American Institute of Physics.

Embedding dynamics for round-off errors near a periodic orbit

We study the propagation of round-off errors near the periodic orbits of a linear map conjugate to a planar rotation with rational rotation number. We embed the two-dimensional discrete phase space (a lattice) in a higher-dimensional torus, where points sharing the same round-off error are uniformly distributed within finitely many convex polyhedra. The embedding dynamics is linear and discontinuous, with algebraic integer coefficients. This representation affords efficient algorithms for classifying and computing the orbits and their exact densities, which we apply to the case of rational rotation number with denominator 7, corresponding to certain algebraic integers of degree three. We provide evidence that the hierarchical arrangement of orbits previously detected in quadratic cases [Lowenstein et al., Chaos 7, 49-66 (1997)] disappears, and that the growth of the number of orbits with the period is algebraic.(c) 2000 American Institute of Physics.

One-dimensional dynamics for traveling fronts in coupled map lattices

Multistable coupled map lattices typically support traveling fronts, separating two adjacent stable phases. We show how the existence of an invariant function describing the front profile allows a reduction of the infinitely dimensional dynamics to a one-dimensional circle homeomorphism, whose rotation number gives the propagation velocity. The mode locking of the velocity with respect to the system parameters then typically follows. We study the behavior of fronts near the boundary of parametric stability, and we explain how the mode locking tends to disappear as we approach the continuum limit of an infinite density of sites.

[The resolution of a mitral valve prosthesis thrombosis with low-dose plasminogen tissue activator and the role of Doppler echocardiographic monitoring]

The case of a 63-year-old woman with a Bjork-Shiley mitral valve prosthesis who developed acute thrombosis of mitral prosthesis and acute pulmonary edema is described. Full clinical success was achieved with medical therapy with tissue-type plasminogen activator. The dosage of drug was titrated by serial echo-Doppler examinations of prosthetic structures and functional area. A low-dose (60 mg over 1 hour) of tissue-type plasminogen activator was sufficient to obtain thrombus resolution. Embolic or hemorrhagic complications were absent. This is the first report of successful use of Doppler echocardiography titrated low-dose of tissue-type plasminogen activator for acute thrombosis of mitral prosthetic valve.