Proton CT on biological phantoms for x-ray CT calibration in proton treatment planning.

Objective.To present and characterize a novel method for x-ray computed tomography (xCT) calibration in proton treatment planning, based on proton CT (pCT) measurements on biological phantoms.Approach.A pCT apparatus was used to perform direct measurements of 3D stopping power relative to water (SPR) maps on stabilized, biological phantoms. Two single-energy xCT calibration curves-i.e. tissue substitutes and stoichiometric-were compared to pCT data. Moreover, a new calibration method based on these data was proposed, and verified against intra- and inter-species variability, dependence on stabilization, beam-hardening conditions, and analysis procedures.Main results.Biological phantoms were verified to be stable in time, with a dependence on temperature conditions, especially in the fat region: (-2.5 0.5) HU °C-1. The pCT measurements were compared with standard xCT calibrations, revealing an average SPR discrepancy within ±1.60% for both fat and muscle regions. In the bone region the xCT calibrations overestimated the pCT-measured SPR of the phantom, with a maximum discrepancy of about +3%. As a result, a new cross-calibration curve was directly extracted from the pCT data. Overall, the SPR uncertainty margin associated with this curve was below 3%; fluctuations in the uncertainty values were observed across the HU range. Cross-calibration curves obtained with phantoms made of different animal species and anatomical parts were reproducible with SPR discrepancies within 3%. Moreover, the stabilization procedure did not affect the resulting curve within a 2.2% SPR deviation. Finally, the cross-calibration curve was affected by the beam-hardening conditions on xCTs, especially in the bone region, while dependencies below 2% resulted from the image registration procedure.Significance.Our results showed that pCT measurements on biological phantoms may provide an accurate method for the verification of current xCT calibrations and may represent a tool for the implementation of a new calibration method for proton treatment planning.

Controlled Carboxylic Acid-Functionalized Silicon Nitride Surfaces through Supersonic Molecular Beam Deposition.

The functionalization of inorganic surfaces by organic functional molecules is a viable and promising method towards the realization of novel classes of biosensing devices. The proper comprehension of the chemical properties of the interface, as well as of the number of active binding sites for bioreceptor molecules are characteristics that will determine the interaction of the sensor with the analyte, and thus its final efficiency. We present a new and reliable surface functionalization route based on supersonic molecular beam deposition (SuMBD) using 2,6-naphthalene dicarboxylic acid as a bi-functional molecular linker on the chemically inert silicon nitride surface to further allow for stable and homogeneous attachment of biomolecules. The kinetically activated binding of the molecular layer to silicon nitride and the growth as a function of deposition time was studied by X-ray photoelectron spectroscopy, and the properties of films with different thicknesses were investigated by optical and vibrational spectroscopies. After subsequent attachment of a biological probe, fluorescence analysis was used to estimate the molecular layer's surface density. The successful functionalization of silicon nitride surface via SuMBD and the detailed growth and interface analysis paves the way for reliably attaching bioreceptor molecules onto the silicon nitride surface.

The effects of primary care monitoring strategies on COVID-19 related hospitalisation and mortality: a retrospective electronic medical records review in a northern Italian province, the MAGMA study.

BACKGROUND: Most symptomatic SARS-CoV-2 infections produce mild to moderate symptoms. Although most patients are managed in the outpatient setting, little is known about the effect of general practitioners' (GP) management strategies on the outcomes of COVID-19 outpatients in Italy. OBJECTIVES: Describe the management of Italian GPs of SARS-CoV-2 infected adult patients and explore whether GP active care and monitoring are associated with reducing hospitalisation and death. METHODS: Retrospective observational study of SARS-CoV-2 infected adult outpatients managed by GPs in Modena (Italy) from March 2020 to April 2021. Information on management and monitoring strategies, patients' socio-demographic characteristics, comorbidities, and outcomes (hospitalisation and death due to COVID-19) were retrieved through an electronic medical record review and analysed descriptively and through multiple logistic regression. RESULTS: Out of the 5340 patients from 46 GPs included in the study, 3014 (56%) received remote monitoring, and 840 (16%) had at least one home visit. More than 85% of severe or critical patients were actively monitored (73% daily) and 52% were visited at home. Changes over time in patients' therapeutic management were observed in concordance with the guidelines' release. Active daily remote monitoring and home visits were strongly associated with reduced hospitalisation rate (OR 0.52, 95% CI 0.33-0.80 and OR 0.50, 95% CI 0.33-0.78 respectively). CONCLUSION: GPs effectively managed an increasing number of outpatients during the first waves of the pandemic. Active monitoring and home visits were associated with reduced hospitalisation in COVID-19 outpatients.

Effect of Process Conditions and Colloidal Properties of Cellulose Nanocrystals Suspensions on the Production of Hydrogel Beads.

The influence of the physical, rheological, and process parameters on the cellulose nanocrystal (CNC) drops before and after external gelation in a CaCl2 solution was investigated. The dominant role of the CNC's colloidal suspension properties, such as the viscous force, inertial, and surface tension forces in the fluid dynamics was quantitatively evaluated in the formation of drops and jellified beads. The similarity and difference between the behavior of carbohydrate polymers and rod-like crystallites such as CNC were enlightened. Pump-driven and centrifugally-driven external gelation approaches were followed to obtain CNC hydrogel beads with tunable size and regular shape. A superior morphological control-that is, a more regular shape and smaller dimension of the beads-were obtained by centrifugal force-driven gelation. These results suggest that even by using a simple set-up and a low-speed centrifuge device, the extrusion of a colloidal solution through a small nozzle under a centrifugal field is an efficient approach for the production of CNC hydrogel beads with good reproducibility, control over the bead morphology and size monodispersion.

Composite nanocellulose-based hydrogels with spatially oriented degradation and retarded release of macromolecules.

The oral delivery of macromolecular therapeutics to the intestinal tract requires novel, robust, and controlled formulations. Here, we report on fabrication by molding of composite hydrogel cylinders made of cellulose nanocrystals (CNCs) and chitosan (Cht) and their performance as delivery vehicles. CNCs provide excellent mechanical and chemical stress resistance, whereas Cht allows scaffold degradation by enzyme digestion. The release of a representative medium size protein (bovine serum albumin) dispersed in the hydrogel is slow and shows a sigmoidal profile; meanwhile, the hydrogel scaffold degrades according to a preferred route, that is the cylinder is eroded along the vertical axis. The cup-like, scarcely interconnected porous network, with a gradient of hardness along the cylinder axis, and the compact skin-like layer covering the lateral wall which stayed in contact with the mold during gelification, explain the preferred erosion direction and the long-term protein release. The possible effect of the molding process on hydrogel structure suggests that molding could be a simple and cheap way to favor surface compaction and directional scaffold degradation.

Porous Si Microparticles Infiltrated with Magnetic Nanospheres.

Porous silicon (pSi) microparticles obtained by porosification of crystalline silicon wafers have unique optical properties that, together with biodegradability, biocompatibility and absence of immunogenicity, are fundamental characteristics to candidate them as tracers in optical imaging techniques and as drug carriers. In this work, we focus on the possibility to track down the pSi microparticles also by MRI (magnetic resonance imaging), thus realizing a comprehensive tool for theranostic applications, i.e., the combination of therapy and diagnostics. We have developed and tested an easy, quick and low-cost protocol to infiltrate the COOH-functionalized pSi microparticles pores (tens of nanometers about) with magnetic nanospheres (SPIONs-Super Paramagnetic Iron Oxide Nanoparticles, about 5-7 nm) and allow an electrostatic interaction. The structural properties and the elemental composition were investigated by electron microscopy techniques coupled to elemental analysis to demonstrate the effective attachment of the SPIONs along the pores' surface of the pSi microparticles. The magnetic properties were investigated under an external magnetic field to determine the relaxivity properties of the material and resulting in an alteration of the relaxivity of water due to the SPIONs presence, clearly demonstrating the effectiveness of the easy functionalization protocol proposed.

In vitro toxicity assessment of hydrogel patches obtained by cation-induced cross-linking of rod-like cellulose nanocrystals.

With the purpose of designing active patches for photodynamic therapy of melanoma, transparent and soft hydrogel membranes (HMs) have been fabricated by cation-induced gelation of rod-like cellulose nanocrystals (CNCs) bearing negatively charged carboxylic groups. Na+ , Ca2+ , Mg2+ have been used as cross-linkers of cellulose nanocrystal (CNC). The biosafety of this material and of its precursors has been evaluated in vitro in cell cultures. Morphological changes, cell organelles integrity, and cell survival with the tetrazolium salt reduction (MTT) assay were utilized as tests of cytotoxicity. Preliminary investigation was performed by addition of the hydrogel components to the cell culture medium and by incubations of the CNC-HM in direct and indirect contact with a confluent monolayer of A375 melanoma cells. Direct contact assays suffered from interference of physical stress. Careful evaluation of cytotoxicity was obtained considering the overall picture provided by microscopy and biochemical tests performed with the CNC-HM in indirect contact with two melanoma cell lines (A375, M14) and human fibroblasts. CNCs have been demonstrated to be a safe precursor material and CNC-HMs have a good biocompatibility provided that the excess of cations, in particular of Ca2+ is removed. These results indicate that CNC and can be safely used to fabricate biomedical devices such as transparent hydrogel patches, although attention must be paid to the fabrication procedure.

Home care for heart failure: can caregiver education prevent hospital admissions? A randomized trial in primary care.

AIM: To assess the feasibility and effectiveness of a low-complexity, low-cost model of caregiver education in primary care, targeted to reduce hospitalizations of heart failure patients. METHODS: A cluster-randomized, controlled, open trial was proposed to general practitioners, who were invited to identify patients with heart failure, exclusively managed at home and continuously attended by a caregiver. Participating general practitioners were then randomized to: usual treatment; caregiver education (educational session for recognizing early symptoms/signs of heart failure, with recording in a diary of a series of patient parameters, including body weight, blood pressure, heart rate). The patients were observed at baseline and during a 12-month follow-up. RESULTS: Three hundred and thirteen patients were enrolled (163 in the intervention, 150 in the usual care group), 63% women, mean age 85.3 ±â€Š7.7 years. At the end of the 12-month follow-up, a trend towards a lower incidence of hospitalizations was observed in the intervention group (hazard ratio 0.73; 95% CI 0.53-1.01 P = 0.061). Subgroup analysis showed that for patients with persistent/permanent atrial fibrillation, age less than 90 years or Barthel score equal to or greater than 50 a significant lower hospital admission rate occurred in the intervention group (hazard ratio 0.63; 95% CI 0.39-0.99; P = 0.048, hazard ratio 0.66; 95% CI 0.45-0.97; P = 0.036 and hazard ratio 0.61; 95% CI 0.41-0.89; P = 0.011, respectively). CONCLUSION: Caregivers training for early recognition of symptoms/signs of worsening heart failure may be effective in reducing hospitalizations, although the benefit was evident only in specific patient subgroups (with persistent/permanent atrial fibrillation, age <90 years or Barthel score ≥ 50), with only a positive trend in the whole cohort. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03389841.

Hybrid deterministic/stochastic simulation of complex biochemical systems.

In a biological cell, cellular functions and the genetic regulatory apparatus are implemented and controlled by complex networks of chemical reactions involving genes, proteins, and enzymes. Accurate computational models are indispensable means for understanding the mechanisms behind the evolution of a complex system, not always explored with wet lab experiments. To serve their purpose, computational models, however, should be able to describe and simulate the complexity of a biological system in many of its aspects. Moreover, it should be implemented by efficient algorithms requiring the shortest possible execution time, to avoid enlarging excessively the time elapsing between data analysis and any subsequent experiment. Besides the features of their topological structure, the complexity of biological networks also refers to their dynamics, that is often non-linear and stiff. The stiffness is due to the presence of molecular species whose abundance fluctuates by many orders of magnitude. A fully stochastic simulation of a stiff system is computationally time-expensive. On the other hand, continuous models are less costly, but they fail to capture the stochastic behaviour of small populations of molecular species. We introduce a new efficient hybrid stochastic-deterministic computational model and the software tool MoBioS (MOlecular Biology Simulator) implementing it. The mathematical model of MoBioS uses continuous differential equations to describe the deterministic reactions and a Gillespie-like algorithm to describe the stochastic ones. Unlike the majority of current hybrid methods, the MoBioS algorithm divides the reactions' set into fast reactions, moderate reactions, and slow reactions and implements a hysteresis switching between the stochastic model and the deterministic model. Fast reactions are approximated as continuous-deterministic processes and modelled by deterministic rate equations. Moderate reactions are those whose reaction waiting time is greater than the fast reaction waiting time but smaller than the slow reaction waiting time. A moderate reaction is approximated as a stochastic (deterministic) process if it was classified as a stochastic (deterministic) process at the time at which it crosses the threshold of low (high) waiting time. A Gillespie First Reaction Method is implemented to select and execute the slow reactions. The performances of MoBios were tested on a typical example of hybrid dynamics: that is the DNA transcription regulation. The simulated dynamic profile of the reagents' abundance and the estimate of the error introduced by the fully deterministic approach were used to evaluate the consistency of the computational model and that of the software tool.

Optical Study of Diamine Coupling on Carboxyl-Functionalized Mesoporous Silicon.

A functionalization strategy, consisting of a silylation reaction by acrylic acid followed by diamine coupling, preserves and stabilizes the photoluminescence (PL) of porous silicon (pSi) microparticles suspended in ethanol. We found that under the condition of efficient amine coupling, besides the orange emission typical of the native pSi, an emission band in the blue region appears. The investigation of the interaction between pSi and diamine shows that diamine quenches and shifts the orange band meanwhile it induces an increase of the intensity of the blue one. PL lifetimes of the orange and blue bands are in the micro and nano second range, respectively. These values and their wavelength dependence clearly prove that the two bands have different origin: quantum confinement and nitrogen impurities introduced at silicon/silicon oxide interface, respectively. Thus, they can be used to discriminate between the pSi microparticles obtained by silylation, which expose carboxylic groups and the pSi microparticles after the diamine coupling, which bear amine functionalities at the surface. The increase in the stability of the PL emission of pSi in aqueous solution after functionalization, with quantum yields of the order of 1­2%, supports the use in biological systems of these brightly emitting, largely porous microparticles, bearing positive or negative surface charge.

Reaction rates of α-tocopheroxyl radicals confined in micelles and in human plasma lipoproteins.

α-Tocopherol, the main component of vitamin E, traps highly reactive radicals which otherwise might react with lipids present in plasmatic lipoproteins or in cell membranes. The α-tocopheroxyl radicals generated by this process have also a pro-oxidant action which is contrasted by their reaction with ascorbate or by bimolecular self-reaction (dismutation). The kinetics of this bimolecular self-reaction were explored in solution such as ethanol, and in heterogeneous systems such as deoxycholic acid micelles and in human plasma. According to ESR measurements, the kinetic rate constant (2k(d)) of the bimolecular self-reaction of α-tocopheroxyl radicals in micelles and in human plasma was calculated to be of the order of 10(5) M(-1) s(-1) at 37 °C. This value was obtained considering that the reactive radicals are confined into the micellar pseudophase and is one to two orders of magnitude higher than the value we found in homogeneous phase. The physiological significance of this high value is discussed considering the competition between bimolecular self-reaction and the α-tocopheroxyl radical recycling by ascorbate.

Investigation of non-specific signals in nanoporous flow-through and flow-over based sensors.

Porous materials are ideal hosts to fabricate high sensitivity devices. Their large specific area and the possibility to modify the type and the strength of the matrix-analyte interactions allow the realization of sensors with finely tailored characteristics. In this article, we investigate how mass transport across the nanoporous structure influences the response due to the non-specific signal by comparing flow-through versus flow-over geometries. We observed a systematic overestimation of the sensitivity for porous substrate devices made of closed-ended pores compared with open-ended pore ones. Our analysis shows that such an effect is due to (unbound) analytes or contaminants that remain trapped within the pores and are not removed by rinsing of the sample. This result was verified by measuring similar samples in both flow through and flow over configurations, as well as their residual response after blockage of all their active sites. We also notice that sensors based on free-standing membranes show similar results independent of the fact that mass transport is induced by either an external pressure source or simply by Brownian motions.

Stable aqueous solutions of naked titanate nanotubes.

Aqueous solutions of naked nanotubes with Ti concentration up to 10 mM are obtained by hydrothermal synthesis followed by extensive ultrasound treatment. The morphology, surface characteristics, and solution behavior of the solubilized nanotubes are investigated. The time course of the solubilization process driven by ultrasound follows a first-order kinetic law and is mediated by the competition between Na(+) and H(+) for surface sites. The dynamics of interaction with small cations (i.e. the sodium ion) is studied by nuclear magnetic resonance spectroscopy and is demonstrated to be a multifaced process, since Na(+) is in part free to exchange between the binding sites on nanotubes and the bulk and in part is confined to slowly exchanging nanotube sites. The aqueous titanate nanotube solutions are stable for months, thus opening new perspectives for the use of this material in drug delivery and in homogeneous photocatalysis.

Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions.

Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.

Deoxycholate as an efficient coating agent for hydrophilic silicon nanocrystals.

Silicon nanocrystals were made hydrophilic by 10-undecenoic acid grafting and were then coated with sodium deoxycholate, a detergent-like compound belonging to the bile acid class which is crucial for absorption of lipids in the small intestine. The resulting silicon nanocrystals have an average diameter of 3-5 nm, can be dispersed in aqueous solutions and show stable photoluminescence. Coating with non-biological surfactants, which are dangerous for cell safety, was investigated for comparison. Results indicate that deoxycholate is a stabilizer of luminescent silicon nanocrystals. Deoxycholate coated nanocrystals appear suitable for applications as multifunctional probes in biomedicine.

Active site residue involvement in monoamine or diamine oxidation catalysed by pea seedling amine oxidase.

The structures of copper amine oxidases from various sources show good similarity, suggesting similar catalytic mechanisms for all members of this enzyme family. However, the optimal substrates for each member differ, depending on the source of the enzyme and its location. The structural factors underlying substrate selectivity still remain to be discovered. With this in view, we examined the kinetic behaviour of pea seedling amine oxidase with cadaverine and hexylamine, the first bearing two, and the second only one, positively charged amino group. The dependence of K(m) and catalytic constant (k(c)) values on pH, ionic strength and temperature indicates that binding of the monoamine is driven by hydrophobic interactions. Instead, binding of the diamine is strongly facilitated by electrostatic factors, controlled by polar side-chains and two titratable residues present in the active site. The position of the docked substrate is also essential for the participation of titratable amino acid residues in the following catalytic steps. A new mechanistic model explaining the substrate-dependent kinetics of the reaction is discussed.

A structure-activity study to identify novel and efficient substrates of the human semicarbazide-sensitive amine oxidase/VAP-1 enzyme.

Kinetic studies were performed with various alkanamines as "substrate probes" of the properties of the active site of the human semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1). We found that the enzyme-substrate recognition step is mainly controlled by apolar interactions and that a "good" substrate has a molecular structure containing a long aliphatic chain and a second positive charge at a distance greater than 12 A from the reactive amino group. In this context, we identified a novel substrate for the human SSAO/VAP-1, 1,12-diaminododecane (DIADO), which is characterised by the highest catalytic efficiency reported to date in comparison to the prototypic substrate benzylamine. Computational docking studies revealed the structural basis of this behaviour, highlighting the key role played by Lys393 in hindering substrate docking. Maximum SSAO/VAP-1 activity is reached at relatively low concentrations of DIADO (10-30 microM), and, in these conditions, it has good selectivity: it is a good substrate of SSAO/VAP-1 but not of human adipocyte monoamine oxidases or pig kidney diamine oxidase. From these findings, it appears that DIADO can be used as a new substrate for human SSAO/VAP-1 to elicit glucose transport into adipocytes, and may consequently have potential pharmacological applications in the design of anti-diabetic agents.

[Computerized medical records in monitoring hypertension. Longitudinal and horizontal evaluation of 25 general practitioners in a primary care setting of Modena, Italy]. / Monitoraggio del paziente iperteso attraverso l'utilizzo della cartella clinica informatizzata. Valutazione longitudinale e trasversale dell'attività di 25 Medici di Medicina Generale della azienda Unità Sanitaria Locale di Modena.

This study aims at evaluating the effectiveness of a computerized-based Clinical Record in monitoring hypertension in a Primary Care Setting. Blood pressure (BP) recording increased by 62% to 70% in the years 2004 to 2006. No improvement, however, was noticeable in the achievement of gold-standard targets in BP control (62% in all period). At the end of 2006 BP was recorded in 65% of patients. Among them, 2/3 of the non diabetics reached < 140/90 mmHg standard, while only 23% of diabetics reached < 130/80 mmHg standard. In conclusion, using a computerized clinical record appears not to be sufficient to obtain good clinical performances, yet it is a necessary first step to clinical audit.

Fast and simple method for the simultaneous evaluation of the capacity and efficiency of food antioxidants in trapping peroxyl radicals in an intestinal model system.

A simple oxygraphic method, for which the theoretical and experimental bases have been recently revised, has been successfully applied to evaluate the peroxyl radical chain-breaking characteristics of some typical food antioxidants in micelle systems, among which is a system that reproduces conditions present in the upper part of the digestive tract, where the absorption and digestion of lipids occur. This method permits one to obtain from a single experimental run the peroxyl radical trapping capacity (PRTC, that is, the number of moles of peroxyl radicals trapped by a given amount of food), the peroxyl radical trapping efficiency (PRTE, that is, the reciprocal of the amount of food that reduces to half the steady-state concentration of peroxyl radicals), and the half-life of the antioxidant ( t(1/2)) when only a small fraction of peroxyl radicals reacts with the antioxidants present in foods. Examples of application of the method to various types of foodstuffs have been reported, assessing the general validity of the method in the simple and fast evaluation of the above-reported fundamental antioxidant characteristics of foods.

Peroxyl radical trapping activity of anthocyanins and generation of free radical intermediates.

The inhibition by anthocyanins of the free radical-mediated peroxidation of linoleic acid in a SDS micelle system was studied at pH 7.4 and at 37 degrees C, by oxygraphic and ESR tecniques. The number of peroxyl radicals trapped by anthocyanins and the efficiency of these molecules in the trapping reaction, which are two fundamental aspects of the antioxidant action, were measured and discussed in the light of the molecular structure. In particular the contribution of the substituents to the efficiency is -OH>-OCH(3)>-H. By ESR we found that the free radicals of anthocyanins are generated in the inhibition of the peroxidation of linoleic acid. The life time of these radical intermediates, the concentration of which ranges from 7 to 59 nM under our experimental conditions, is strictly correlated with the anthocyanin efficiency and with the heat of formation of the radical, as calculated by a semiempirical molecular orbital approach.