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BackgroundHealthcare workers (HCW) are at increased risk of being infected with SARS-CoV-2, yet limited information is available on risk factors of infection.MethodsWe pooled data on occupational surveillance of 10,654 HCW who were tested for SARS-CoV-2 infection in six Italian centers. Information was available on demographics, job title, department of employment, source of exposure, use of personal protective equipment (PPE), and COVID-19-related symptoms. We fitted multivariable logistic regression models to calculate odds ratios (OR) and 95% confidence intervals (CI).FindingsThe prevalence of infection varied across centers and ranged from 3.0% to 22.0%, being strongly correlated with that of the respective areas. Women were at lower risk of infection compared to men. Fever, cough, dyspnea and malaise were the symptoms most strongly associated with infection, together with anosmia and ageusia. No differences in the risk of infection were detected between job titles, or working in a COVID-19 designated department. Reported contact with a patient inside or outside the workplace was a risk factor. Use of a mask was strongly protective against risk of infection as was use of gloves. The use of a mask by the source of exposure (patient or colleague) had an independent effect in reducing infection risk.

Introduction: Few data on the diagnostic performance of serological tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are currently available. We evaluated sensitivity and specificity of five different widely used commercial serological assays for the detection of SARS-CoV-2–specific IgG, IgM, and IgA antibodies using reverse transcriptase-PCR assay in nasopharyngeal swab as reference standard test.Methods: A total of 337 plasma samples collected in the period April–June 2020 from SARS-CoV-2 RT-PCR positive (n = 207) and negative (n = 130) subjects were investigated by one point-of-care lateral flow immunochromatographic assay (LFIA IgG and IgM, Technogenetics) and four fully automated assays: two chemiluminescence immunoassays (CLIA-iFlash IgG and IgM, Shenzhen YHLO Biotech and CLIA-LIAISON® XL IgG, DiaSorin), one electrochemiluminescence immunoassay (ECLIA-Elecsys® total predominant IgG, Roche), and one enzyme-linked immunosorbent assay (ELISA IgA, Euroimmune).Results: The overall sensitivity of all IgG serological assays was >80% and the specificity was >97%. The sensitivity of IgG assays was lower within 2 weeks from the onset of symptoms ranging from 70.8 to 80%. The LFIA and CLIA-iFlash IgM showed an overall low sensitivity of 47.6 and 54.6%, while the specificity was 98.5 and 96.2%, respectively. The ELISA IgA yielded a sensitivity of 84.3% and specificity of 81.7%. However, the ELISA IgA result was indeterminate in 11.7% of cases.Conclusions: IgG serological assays seem to be a reliable tool for the retrospective diagnosis of SARS-CoV-2 infection. IgM assays seem to have a low sensitivity and IgA assay is limited by a substantial rate of indeterminate results.

Gabriella Di Felice,1 Paolo Colombo2 1National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, 2Institute of Biomedicine and Molecular Immunology, National Research Council, Palermo, Italy Abstract: Allergen-specific immunotherapy was introduced in clinical settings more than 100years ago. It remains the only curative approach to treating allergic disorders that amelioratessymptoms, reduces medication costs, and blocks the onset of new sensitizations. Despite this clinical evidence and knowledge of some immunological mechanisms, there remain some open questions regarding the safety and efficacy of this treatment. This suggests the need for novel therapeutic approaches that attempt to reduce the dose and frequency of treatment administration, improving patient compliance, and reducing costs. In this context, the use of novel adjuvants has been proposed and, in recent years, biomedical applications using nanoparticles have been exploited in the attempt to find formulations with improved stability, bioavailability, favorable biodistribution profiles, and the capability of targeting specific cell populations. Inthis article, we review some of the most relevant regulatory aspects and challenges concerning nanoparticle-based formulations with immunomodulatory potential, their related immunosafety issues, and the nature of the nanoparticles most widely employed in the allergy field. Furthermore, we report invitro and in vivo data published using allergen/nanoparticle systems, discuss their impact on the immune system in terms of immunomodulatory activity and the reduction of side effects, and show that this strategy is a novel and promising tool for the development of allergy vaccines. Keywords: allergy, nanocarriers, immunotoxicity, immune modulation, immunotherapy, allergens

This paper presents two modelling strategies for the simulation of low velocity impact induced damage onset and evolution in composite plates. Both the strategies use a global–local technique to refine the mesh in the impact zone in order to increase the accuracy in predicting the impact phenomena without affecting the computational cost. Cohesive elements are used to simulate the inter-lamina damage behaviour (delaminations) and Hashin’s failure criteria are adopted to predict the intra-lamina failure mechanisms. The two modelling strategies differ in terms of input parameters for the inter-lamina and intra-lamina damage evolution laws and in terms of modelling solutions in the impacted area. Comparisons between numerical and experimental results on composite plates subjected to different impact energies, according to the ASTM D7136 requirements, have been used to assess the peculiarities and the fields of application for the two proposed modelling strategies. Both the strategies have been tested by adopting the finite element code ABAQUS®. The different approaches to set the parameters of cohesive elements’ constitutive laws and Hashin’s criteria and the different choices made in quantifying the dependence of failure criteria on the finite elements’ average size have been taken into account.

Impact induced damage is ofter of main concern for aeronautic structures. The aircraft can undergo low velocity impacts during the assembly stage and during its operative life. Delamination and other damage mechanisms, such as matrix cracks, fibre-matrix debonding and fiber breakages can be the consequence of impact events with foreign objects under in service conditions and maintenance operations. Dam-ages induced by low velocity impacts can be hardly detected by visual inspections because they often are confined deeply in the laminate thickness. Hence the use of expensive and time consuming non-destructive techniques such as ultrasonic tests, can be required. In order to prevent catastrophic events, as a consequence of impacts, designers usually increase the structural safety margins thereby increasing the weight of the aircraft. In the frame of the present work, in order to quantify the influence of impact events on the load carrying capability of complex composite structures, specific advanced numerical techniques are used to take into account the skin-stringer debonding phenomena arising in stiffened composite panels as a consequence of low velocity impact events.

In this paper, a numerical study on the skin-stringer debonding growth in composite panels under compressive load is presented. A novel numerical procedure, for the selection of proper material parameters governing the traction-separation law in Cohesive Zone Model (CZM) based elements, is introduced and demonstrated. Indeed, the proposed procedure uses Virtual Crack Closure Technique based FEM analyses on Double Cantilever Beam (DCB) and End Notched Flexure (ENF) specimen to characterize the traction-separation law, respectively, for fracture mode I and mode II. The established traction-separation laws are, then, applied to composite structures containing inter-laminar damages modeled by cohesive elements. To validate the proposed approach, a single stringer panel under compression with an artificial debonding between skin and stringer, has been considered, he numerical results, in terms of displacements and debonding size as a function of applied compressive load, have been compared to experimental data available in literature.

L’endotossina è una tossina microbica, parte integrante della membrana esterna della parete di batteri Gram-negativi che viene rilasciata completamente con la lisi del batterio. È costituita da sub-unita’ molecolari che hanno dimensioni comprese tra 10.000 e 20.000 Daltons, mentre le aggregazioni hanno dimensioni di circa 100.000 Daltons. Un esempio tipico di endotossina è rappresentato dal lipopolisaccaride (LPS) che è presente nella membrana esterna dei batteri Gram-negativi. Le endotossine sono le principali responsabili delle conseguenze cliniche delle infezioni da batteri gram-negativi. Infatti, l’endotossina è ritenuta responsabile della patogenesi della sepsi, dello shock settico e della conseguente malattia multiorgano (MOF) (1). A causa della sua natura particolarmente aggressiva e multifattoriale, la sepsi conduce rapidamente a morte e costituisce la principale causa di decesso nelle terapie intensive non coronariche di tutto il mondo. Da qui la necessità, per la cura della sepsi, di rimuovere e/o disattivare le endotossine dal corpo del paziente prima che la malattia degeneri. Infatti, in relazione alla presenza di endotossina nel sangue si innesca una complessa attivazione immunologica che coinvolge vari sistemi biologici (immunitario e reticoloendoteliale) e una serie di mediatori, liberati principalmente dall’attivazione di macrofagi, monociti e altre cellule. Inoltre, le endotossine sono contaminanti frequenti del DNA plasmidico estratto dai batteri e di tutti quei prodotti che sono estratti e/o sono venuti a contatto con essi. Le endotossine devono essere rimosse da questi prodotti per evitare reazioni infiammatorie nel corso delle applicazioni in vivo, quali ad esempio la terapia genica. Dal punto di vista terapeutico, negli ultimi anni hanno assunto un ruolo rilevante una classe di proteine e/o peptidi (e loro derivati) che, come prodotti dell’immunità innata, sono in grado di legare e neutralizzare componenti della parete batterica tra cui l’LPS. I peptidi che sono in grado di neutralizzare questo tipo di processo vengono oggi definiti con un termine ampio quale quello di Host Defense Peptide (HDP). Quest’ultima classe di proteine sono di particolare interesse in quanto oltre all’attività antimicrobica diretta, sono in grado di potenziare la risposta immunitaria dell’organismo, promuovendo in vitro varie risposte di difesa (ad es. migrazione di leucociti, maturazione delle cellule dendritiche) e contribuendo così al potenziamento della risposta immunitaria adattativa. Queste proteine sono generalmente caratterizzate dall’avere un peso molecolare compreso tra 2 ed 80 kDa e in maniera preferenziale, contenenti amino-acidi caricati positivamente (da qui il termine di proteine cationiche) (2). Le proteine denominate non specific Lipid Transfer proteins (ns-LTPs) sono piccole molecole proteiche particolarmente stabili di approssimativamente 10 KDa solitamente presenti in tutti gli organismi vegetali sino ad oggi studiati (3). Tali proteine sono accomunate dalla capacità di promuovere, in vitro, il trasferimento di molecole lipidiche attraverso membrane anche se, studi recenti, hanno dimostrato che esse sembrano svolgere una funzione protettiva in quanto capaci di agire come peptidi ad attività antimicrobica. In alcune specie vegetali è stata dimostrata una loro capacità allergenica come nel caso delle Rosaceae Prunoideae (pesca, albicocca, prugna), Pomoideae (mela) e le Urticacee quali la Parietaria (4). La tecnologia del DNA ricombinante ha permesso l’isolamento di vari allergeni della famiglia delle proteine ns- LTPs, tra questi quelli della Parietaria denominati Parj1 e Parj2. In particolare, sono state ad oggi isolate due isoforme dell’allergene Parj1 denominate (secondo la nomenclatura internazionale) Parj1.01 e Par1.02 (5, 6). Tali isoforme differiscono essenzialmente per la presenza di una regione di 37 aminoacidi presente esclusivamente nell’isoforma Parj1.01 (7). Caratterizzazione di un peptide in grado di legare LPS batterico Una analisi in silico condotta mediante l’algoritmo messo a disposizione dall’Antimicrobial Peptide Database ha messo in evidenza che la porzione carbossiterminale del Parj1.01 presenta caratteristiche biochimiche peculiari. Tale regione presenta una carica netta totale positiva (+5) e una elevata percentuale di residui di prolina suggerendo che tale peptide possa avere la capacità di agire come peptide ad attività antimicrobica. I dati riportati in Tabella 1 descrivono la diversa capacità delle due isoforme ricombinanti dell’allergene maggiore Parj1 (Parj1.01 e Parj1.02) di legare LPS di origine batterica. I dati mostrati evidenziano come l’isoforma Parj1.01 presenti una spiccta capacità di legare LPS. Tabella 1. Saggi di determinazione della quantità di endotossina endogena Quantità di proteina analizzata Positività al LAL test rParj1.01 rParj1.02 1 μg

Allergen extracts have been used for diagnosis and treatment of allergy for around 100 years. During the second half of 20th century, the notion increasingly gained foothold that accurate standardization of such extracts is of great importance for improvement of their quality. As a consequence, manufacturers have implemented extensive protocols for standardization and quality control. These protocols have overall IgE-binding potencies as their focus. Unfortunately, each company is using their own in-house reference materials and their own unique units to express potencies. This does not facilitate comparison of different products. During the last decades, most major allergens of relevant allergen sources have been identified and it has been established that effective immunotherapy requires certain minimum quantities of these allergens to be present in the administered maintenance dose. Therefore, the idea developed to introduce major allergens measurements into standardization protocols. Such protocols based on mass units of major allergen, quantify the active ingredients of the treatment and will at the same time allow comparison of competitor products. In 2001, an EU funded project, the CREATE project, was started to support introduction of major allergen based standardization. The aim of the project was to evaluate the use of recombinant allergens as reference materials and of ELISA assays for major allergen measurements. This paper gives an overview of the achievements of the CREATE project.

An improved method for the study of copper metabolism in Wilson's disease, using a stable, rather than radioactive, copper isotope (65Cu) has recently been described. We report on the use of this method for the study of a family with two members affected by Wilson's disease.The family comprised parents and four siblings: one 20-year-old male and three females, aged 22, 17 and 5 years, respectively. The boy and the 17-year-old girl both presented with liver cirrhosis. Diagnosis of Wilson's disease was suggested by elevated liver copper content and/or low caeruloplasmin levels and Kayser-Fleischer ring.All family members were given an oral dose of 3 mg of 65Cu. Blood samples were taken at 0, 1, 2, 6, 24, 48, and 72 hours. In 4 subjects, additional blood samples were drawn at 7, 14 and 21 days after dosage. The ratio 65Cu:63Cu in serum was determined in all samples by means of Inductively Coupled Plasma Mass Spectrometry.The diagnosis of Wilson's disease was confirmed in the two symptomatic members by the unequivocal decrease observed in the 65Cu percent enrichment, which approached zero by 72 hours. In contrast, Wilson's disease could be definitely excluded in both siblings, one of whom only 5 years old, on the evidence of net secondary peaks, showing normal incorporation of 65Cu into caeruloplasmin. These findings were later confirmed by genetic analysis. Parents, who carried defective genes with different mutations, also showed different abnormalities of copper metabolism.The oral test with the stable copper isotope 65Cu is a safe, non invasive option able to exclude Wilson's disease in patients with a difficult diagnosis or in a presymptomatic stage. However, positive tests must still be confirmed by copper dosage in liver biopsies, as heterozygotes can present with severe alterations of copper metabolism, without developing symptoms of the disease. The use of this test in conjunction with genetic analysis on a larger number of heterozygous subjects may add to the understanding of the Wilson's disease defect.

Synthetic amorphous silica (SAS) consists of agglomerates and aggregates of primary particles in the nanorange (

International audience; Food additive E551 consists of synthetic amorphous silica (SAS), comprising agglomerates and aggregates of primary particles in the nanorange (

Damage after impact often involves aeronautic structures. The aircraft can be involved in impacts during the assembly stage and operative life. Typical impacts can be related to falling tools, hailstones, debris on the take-off strip thrown against the aircraft by the rolling tyres, maintenance operations. There are two categories of damage impact: Low and High Velocity Impact (LVI, HVI). Damages coming from low velocity impacts are difficult to identify because they are often within the composite structure and the use of non-destructive testing, e.g. ultrasonic test, is not convenient. In order to prevent catastrophic events the designers must increase the safety margin and thereby the weight of the aircraft. The present study shows two different numerical procedures based on finite elements method to investigate on some damage mechanisms of a carbon fibre reinforced plastic (CFRP) structures (e.g. interface debonding, fibre or matrix cracking) and the residual strength of such structures under live loads.

A novel numerical methodology is used to investigate the behavior of an all-composite wing-box under a compressive load taking into account the presence of concurrent inter-laminar damages such as delaminations and skin-stringer debonds and their propagation. The proposed numerical methodology, based on linear structural analyses, is computationally inexpensive if compared to the VCCT and CZM based numerical techniques, hence, it appears to be particularly suitable for the preliminary design phase of complex structure. The presented linear approach is an evolution of a previous technique developed specifically for delaminations. Indeed, in this paper the linear approach has been enhanced to predict the propagation of inter-laminar damages with open crack surfaces such as skin-stringer debonds and it has been implemented in a commercial Finite Element platform. The effectiveness (in terms of computational cost and accuracy of results) of the suggested linear numerical methodology, in predicting the compressive behavior of complex composite structures with inter-laminar damages, has been confirmed by cross-comparisons with the standard non-linear VCCT technique. Finally, comparisons in terms of critical propagation load and Energy Release Rate distribution along the damage tip predictions, for several examined structural configurations with different damage extension and depth, have allowed to assess the field of applicability of the propose novel numerical methodology.

The investigation of the mechanical response of fibre-reinforced composite laminates under impact loads can be very difficult due to the occurrence of simultaneous failure phenomena. Indeed, as a consequence of low velocity impacts, intra-laminar damages, like fibre and matrix cracking, and inter-laminar damages, such as delaminations, can take place simultaneously. These damage mechanisms can lead to significant reductions in strength and stability of the composite structure. In this paper a joint numerical-experimental study is proposed which, by means of non-destructive testing techniques (Ultra-sound and thermography) and non-linear explicit FEM analyses, aims to completely characterise the impact induced damage in composite laminates under low velocity impacts. Indeed the proposed numerical tool has been used to improve the understanding of the experimental data obtained by Non-Destructive Techniques. Applications on samples tested according to the AECMA (European Association of Aerospace Manufacturers) prEn6038 standard at three different impact energies are presented. The interaction between numerical and experimental investigation allowed to obtain an exhaustive insight on the different phases of the impact event considering the inter-laminar damage formation and evolution.

Composite structures are increasingly finding more applications in the aeronautical field as well as the automotive one, thanks to their low weight – performance ratios, in terms of strength and stiffness. However, composite materials, as well known, are characterized by a critical behavior in terms of detectability of damage and performances of damaged components. A critical aspect related to damaged composite structures is, for sure, the repair aimed to restore the original stiffness and strength characteristics of the component depending on the damage typology and location. In this paper, a preliminary repair design tool is presented. The tool is aimed to help the designer by suggesting different repair typologies and proper repair size. This tool, by means of optimization analyses can provide the best repair solution with minimal adhesive shear stress and size of the repair patch. The tool has been tested against a literature case study on multistep composite-metal joints.

In this paper, a numerical study on the skin–stringer debonding growth in composite panels under compressive load is presented. A novel numerical procedure, for the selection of proper material parameters governing the traction–separation law in Cohesive Zone Model (CZM) based elements, is introduced and demonstrated. Indeed, the proposed procedure uses Virtual Crack Closure Technique (VCCT) based FEM analyses on Double Cantilever Beam (DCB) and End Notched Flexure (ENF) specimen to characterize the traction–separation law, respectively, for fracture mode I and mode II. The established traction–separation laws are then applied to composite structures containing inter-laminar damages modeled by cohesive elements. To validate the proposed approach, a single stringer panel under compression with an artificial debonding between skin and stringer, has been considered. The numerical results, in terms of displacements and debonding size as a function of applied compressive load, have been compared to experimental data available in literature providing a good numerical–experimental correlation.

Delamination and other damage mechanisms, such as matrix cracks, fibre-matrix debonding and fiber failure can appear as a consequence of impact events with foreign objects under in service conditions and maintenance operations. These phenomena are seldom analyzed together without discussing how the interferences between the different damage mechanisms can influence their evolution under different loading conditions. The present work is focused on the development of a specific numerical procedure, able to take into account the failure modes interaction in composite laminated structures subject to a low velocity impact. As a matter of fact, a very fine mesh refinement is required to correctly evaluate the stress state where the impact induced damage onsets. Hence, in order to reduce the computational cost without compromising the accuracy of results, a global/local approach, characterized by a very refined mesh in the critical impact region interacting with a coarser mesh in the rest of the geometrical domain, has been implemented in the FE model. In the present work, Multi-Point-Constraints (MPC) has been used to link the refined local domain to the coarse global domain without using transition meshes. The implementation and the analyses have been performed in the ABAQUSA (R) FE environment.

Background The major allergens in Parietaria pollen, Par j 1 and Par j 2, have been identified as lipid transfer proteins. The family of the Par j 1 allergens is composed of two isoforms, which differ by the presence of a 37 amino acid peptide (Par37) exclusive to the Par j 1.0101 isoform. The goal of this study was to elucidate the biological properties of the Par37 peptide. Methods In silico analysis, spectrofluorimetric experiments and in vitro cell culture assays were used to identify the biological properties of Par37. In addition, a mouse model of sensitization was used to study the influence of Par37 in the murine immune response. Results In silico analysis predicted that Par37 displays characteristics of a host defence peptide. Spectrofluorimetric analysis, real-time PCR and ELISA assays demonstrated that Par37 possesses an LPS-binding activity influencing cell signalling in vitro. In RAW264.7 cells, LPS-induced IL-6 and TNF-α transcription and translation were inhibited after preincubation with Par37. Consistent with these data, inhibition of IFN-γ secretion was observed in murine spleen cells and in human PBMC. Finally, mice immunized with the two Par j 1 isoforms differing in the presence or absence of the Par37 peptide showed different immunological behaviours in vivo. Conclusions This study demonstrates that the Par j 1.0101 allergen displays LPS-binding activity due to the presence of a 37 amino acid COOH-terminal region and that this region is capable of influencing cytokine and antibody responses in vitro and in vivo.

Antigenic peptides with substituted side chains inhibit immune responses to a number of recall Ags from infectious agents in vitro. Here we show that the same strategy can be applied to peptides derived from a pollen protein, the major allergen of Parietaria judaica(Par j1), a plant responsible for most allergenic sensitization in the southern Mediterranean area. Three T cell lines responding to Par j1 protein were used to identify a stimulatory peptide. Two different monosubstituted altered peptide ligands (APL) were identified that bound to the HLA-DR of the responders, did not stimulate the T cell lines on their own, and decreased the response to subsaturating amounts of the unmodified stimulatory peptide. Most important, these APL were able to inhibit the response of these cell lines to intact Par j1 protein. A third monosubstituted peptide bound to the HLA-DR but did not show inhibitory activity. The two APL had a lower affinity than the unsubstituted peptide for the HLA-DR. The last two observations make MHC blockade an unlikely explanation for the observed effect. These results indicate the action of a specific peptide-mediated antagonism that may be useful in controlling the T cell component of an allergic response.

IgG antibody response to the inhalant allergen Parietaria judaica (Pj) and IgG subclass distribution were studied in 82 normal subjects, divided into three groups according to age (0-1, 1-20, and 20-60 years) and in 32 allergic subjects aged 20-60 years. Both normal and allergic subjects showed an IgG response, and all had IgG1 antibodies specific for PjE. Serum IgG2, IgG3, and IgG4 against PjE were detectable in 36%, 46%, and 22% of normal subjects, and in 58%, 31%, and 65% of allergic subjects, respectively. A significant difference in class distribution between allergic and age-matched normal subjects was found only for IgG4 antibodies against PjE (65% and 17%; P < 0.01). The ELISA results were also analyzed quantitatively, taking into account the relative proportion of specific antibodies. Thus, in normal subjects IgG1 antibodies showed a decreasing trend as the age rose, while no differences according to the age of the subject were found for IgG2 and IgG4. When data from allergic subjects (20-60 years) and the age-matched normal group were compared, they were different for the relative percentage of IgG2 only, showing for this a significantly lower value (P < 0.001). The present data indicate that normal and allergic subjects show differences in the IgG isotype distribution depending on their sensitivity and duration of allergen exposure.