1,721,079 research outputs found
Chimica generale. Esercizi svolti. Raccolta di esercizi con soluzioni dettagliate per la preparazione alla prova scritta dell'esame di Chimica generale
No full textIl libro offre una ricca raccolta di esercizi che coprono gli argomenti fondamentali della Chimica Generale, partendo dalla nomenclatura e classificazione dei composti inorganici fino agli equilibri in soluzione acquosa. Gli esercizi sono organizzati in modo da fornire una progressione graduale di difficoltà, partendo dai problemi più semplici e procedendo verso quelli di complessità crescente. Gli esercizi proposti rivisitano anche i concetti chimici di base necessari alla loro risoluzione. Questo approccio rende il libro adatto sia all'uso in classe che allo studio individuale, fornendo una formazione completa e approfondita. Il testo è una risorsa preziosa per chiunque desideri approfondire la propria conoscenza della materia o prepararsi all'esame di Stechiometria
Potential use of plants and their extracts in the treatment of coagulation disorders in COVID-19 disease: a narrative review
No full textAbstract: Coronavirus disease, i.e., COVID-19, is caused by the virus called “severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2)”. Infection induces predominantly respiratory illness but is
also associated with coagulation disorders which play an important role in the pathogenesis, clinical
manifestations, and outcome of the disease. The treatment of hemostasis disorders of COVID-19 patients
is a difficult problem to solve. For example, heparin is quite effective drug in reducing mortality in severe
COVID-19 forms but not able to prevent venous and arterial thromboembolic complications. Moreover,
anticoagulant therapy with heparin is associated with several adverse reactions, such as thrombocytopenia,
osteoporosis, hypoaldosteronism and hypersensitivity reactions. New alternative anticoagulant molecules
can be obtained from plants which are rich in polyphenols and flavonoids. These compounds, besides being
potent antioxidants, also possess anti-inflammatory effect and, because able to inhibit the activity of many
enzymes, including serine proteases, also anticoagulant properties. The purpose of this narrative review
is to provide an overview of current literature data on coagulation disorders associated with COVID-19
disease and of the anticoagulant activity of plants and their extracts in order to evaluate their possible clinical
application as alternative sources of novel molecules with anticoagulant and antithrombotic activity for the
treatment of coagulation disorders in patients with COVID-19
FT-IR studies of protein adsorption on polymeric materials: influence of surface structure, hydrophobicity and charge
No full text
The role of fibronectin in cell adhesion to spiral patterned TiO2 nanoparticles
No full textSpiral micropatterned surfaces of decreasing dimensions were produced by photo-immobilising a photoreactive hyaluronan (Hyal) derivative on TiO2 nanoparticles. The microstructured surfaces were characterised by both SEM and AFM analysis. The behaviour, of both endothelial cells (HCAEC) and tumoral mouse fibroblasts (NIH3T3) on the patterned surfaces was evaluated. HCAEC adhered only to the TiO2 nanoparticles avoiding the contact with Hyal. NIH3T3 adhered to and covered completely the TiO2 spiral and prolonging the culture time also the photo-immobilised Hyal. The role of fibronectin to mediate cell adhesion to the TiO2 pattern surfaces was evaluated by experiments with blocked fibronectin membrane receptors on both HCAEC and NIH3T3. The results showed the absence of any adhering cells. Thus, fibronectin seemed to be the only key protein in mediating cell adhesion to these TiO2 substrates
Fibrinogen conformation and platelet reactivity in relation to material-blood interaction: effect of stress hormones
No full textThe performance of many biomaterials in hemocompatibility tests is altered when blood is drawn from
stressed subjects. A salient physiological response during stress is one in which hormones are released into
plasma by the hypothalamo-pituitary-adrenal axis. We investigated the influence of basal and stress levels
of epinephrine and â-endorphin on the conformation of fibrinogen (Fbg), both in saline solution (under
physiological conditions) and after its adsorption to polyethylene (PE), by FT-IR spectroscopy. Moreover,
as Fbg is one of the major mediators of platelet adhesion, the behavior of platelets in contact with PE was
also evaluated as a function of the two different hormone concentrations. Epinephrine was found to affect
Fbg conformation and to increase platelet adhesion to PE at stress level. Basal and stress levels of â-endorphin
did not significantly affect the Fbg conformation and only induced adhesion of isolated platelets to the PE
surface. A direct relationship was therefore found between Fbg conformation and platelet behavior. The
response of platelets was affected by the stress status of donors through the influence of epinephrine on Fbg
conformation
The role of Fibrinogen conformation on platelets activation
No full textAbstract
Platelet adhesion and activation induced by fibrinogen (Fbg) coating on polysaccharide layers of hyaluronic acid (Hyal) and its sulfated derivative (HyalS) were analyzed. Hyal or HyalS was coated and grafted on the glass substrate using a photolithographic method. The Fbg coating was achieved by two different routes: the immobilization of Fbg by means of covalent bond to the polysaccharide layers and the mere adsorption of Fbg to Hyal and HyalS surfaces. Platelet adhesion and activation to the surfaces were evaluated using, respectively, scanning electron microscopy (SEM) and quantifying the release of Platelet Factor 4 by ELISA. The method used for the coating of the surfaces with the Fbg influenced the platelet response. In fact, platelet adhesion and activation took place on surfaces covered by bound Fbg but not on those containing adsorbed Fbg. To explain this difference, the molecular mechanism involved in the Fbg--platelet interaction was investigated blocking platelet membrane receptors by monoclonal antibodies. Because the interaction between Fbg and the GPIIb/IIIa platelet membrane receptor was the only molecular pathway involved, Fbg conformation after the interaction (adsorption or binding) with the Hyal and the HyalS chains and the role of serum proteins adsorbed on the Fbg containing surfaces were accurately analyzed. Both adsorbed and bound Fbg prevented the adsorption of further serum proteins; consequently, a direct interaction between Fbg and platelets was supposed and the different platelet behavior was ascribed to the different conformational changes that occurred after the adsorption and the chemical binding of the Fbg to the Hyal and HyalS surfaces
Platelet adhesion to commercial and modified polymer materials in animals under psychological stress and in a no-stress condition.
No full textIt is well known that stressful stimuli change blood functions and that protein and platelet parameters are altered in humans and animals subjected to stress. We have examined the influence of psychological stress on the morphological responses of platelets on commercially available materials [polyester (VP), fluoropassivated polyester (VPF), non-woven benzylic ester of hyaluronic acid (Hyaff11)] and on materials synthesised (PUPA) and/or surface modified by sulphation (Hyaff11S) or by immobilisation of the anticoagulant molecules heparin and sulphated hyaluronic acid (PUPA-Heparin, PUPA-HyalS, HyalS-PET). Moreover, the anticoagulant activity (i.e. thrombin inactivation) of the materials was analysed. In the no-stress condition, the surfaces with a low degree of platelet adhesion were Hyaff11S, HyalS-PET, PUPA-Heparin and PUPA-HyalS. Hyaff11, PET and PUPA had the highest number of adherent platelets within the series. VP and VPF exhibited an intermediate behaviour. The exposure of animals to stress induced a dramatic change in platelet number and morphology on PET, HyalS-PET, PUPA, PUPA-HyalS and Hyaff11: there was a higher degree of platelet adhesion, increased platelet spreading and the appearance of pseudopodia. In VP, VPF, Hyaff11S and PUPA-Heparin, there were no changes in platelet adhesion in stress conditions with respect to the no-stress condition; the latter two materials, the only ones able to prolong thrombin time, had a very low number of adherent platelets
Chemistry and topographic domains: micropatterned surfaces. Production, physical-chemical and biological characterisation
No full textThe presence of micro and nano-domains on a surface
allows the manipulation of two fundamental external signals: cellsubstrate
and cell-cell interaction, in order to create a pattern of
highly oriented cells capable of arranging themselves in tissue. Cell
guidance also depends on the different chemical and/or
topographic domains present on a surface and on their geometry.
Thus, structures are realised so that they also contain different
chemical and geometrical domains. Among the many known
methods for modifying surfaces, the photoimmobilisation process
is a useful technique for creating microstructures with both
chemical and topographic patterns.
In most approaches, cells are localized to adhesive regions on a
substrate, thus limiting their use to one cell type. More recently,
approaches have been developed for patterning two or more cell
types in spatially defined co-cultures. These approaches can be used to study the effects of cell shape, cell-matrix interactions, and heterotypic cell-cell
contact on various cell functions. Many studies on patterned co-cultures have involved
the selective adhesion of one cell type compared to the normal adhesion of the other.
In this chapter, the results of our research on micro-topography and cell
behaviour are reviewed and discussed.
Patterns with different geometries have been obtained by photoimmobilisation of
the polysaccharide hyaluronic acid (Hyal) on glass surfaces. The resulting surface
patterns have been utilised to study the influence of microstructures as a function of
chemical, topographic and dimensional properties on both primary and tumoral cell
lines. Cell adhesion and distribution have been analysed as a function of the shape and
area of the microdomains.
Studies carried out with the aim to analyse heterotypic cell-cell interaction as a
function of geometry and dimension domains are also reported. In particular, the
possibility of obtaining co-cultured microstructured surfaces by seeding fibroblasts on
patterned samples with already adhered endothelial cells has been investigated.
The chapter ends with an outline of the results recently obtained by other authors
studying the combined effect of topographic domains and mechanical/gravitational
stress, a very promising topic in the field of cell microenvironment topography
- …
