176 research outputs found
The role of plasma proteins and stress in the assesment of hemocompatibility
No full textThe physiological and psychological conditions of subjects supplying blood for hemocompatibility tests significantly affect the behavior of platelets in terms of both adhesion and activation. The responses of platelets to a standard biomaterial, polyethylene (PE), were examined with blood collected from male rabbits both in basal conditions and after stress, Different media were utilized. First, platelet-rich plasma (PRP) was used to obtain a PE response to contact with platelets. Then platelets drawn from PRP were isolated and washed with Krebs-Ringer solution. One aliquot was suspended in serum (Pw-S) where fibrinogen was absent, another aliquot in Krebs-Ringer solution (Pw-KR) tin order to avoid the influence of the plasma proteins on platelets), and a third aliquot in the original plasma from which the platelets were drawn (Pw-PPP) tin order to restore the initial condition of the plasma but with washed platelets). The analysis of platelet adhesion and morphology was performed by Scanning Electron Microscopy (SEM). Differences in platelet adhesion and morphology were observed with four different media in nonstressed animals, with Pw-PPP showing a higher number and Pw-S and PW-KR lower numbers. Platelet morphology indicated low levels of activation. The platelets drawn from stressed subjects could not be counted in either PRP or PPP medium because they were fully aggregated and adhered; in contrast, in Pw-KR and Pw-S, no significant differences were found with respect to nonstressed conditions, and there was little difference in platelet morphology. All of these factors underline the role of plasma proteins, in particular fibrinogen, in the stress-induced activation of platelet
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
Effect of behavioural stress on platelet reactivity on polimeric
No full textIt is well known that stressful stimuli change blood functions and platelet parameters are altered in humans and animals subjected to stress. We have examined the influences of behavioral stress on the morphological responses of platelets on a standard biomaterial, polyethylene (PE). Male rabbits were used, Blood was collected from the marginal vein of the ear 2 times per subject: the first sample was used as the baseline; 1 week later, the second was preceded in half of the subjects by 20 min of immobilization stress. In vitro adhesion of platelets on the PE was evaluated. The exposure of animals to stress induced a dramatic change in platelet morphology and functions on the PE: a higher degree of platelet adhesion, increased platelet spreading, and the appearance of pseudopodia, In the unstressed subjects there were no modifications of the platelets on the PE with respect to the baseline. The present experiment emphasizes for the first time the possible problems involved with the varying physiological conditions of patients before and after any biomaterial application surgery and of subjects who supply the blood for hemocompatibility tests performed on biomaterials. Therefore, in assessments of the performance of different biomaterials, the reactivity of blood factors in the patients should be considered and the test of blood compatibility should be performed with blood collected from donors in appropriate physiological conditions
MAPPING EMOTIONAL RESPONSES ACROSS THE INDIVIDUAL MORAL SYSTEM IN SOCIAL NETWORK ETHICAL PUBLIC COMMUNICATION: A QUASI-EXPERIMENTAL STUDY
No full textSocial networks are meant to be environments of interconnection, but nowadays are emo-tionally charged and fuelled by polarizing dynamics, particularly on ethical issues. What appear to be overlooked are the moral motivational systems that can moderate emotional responses prompted by the communicative online content. Based on the individual Moral Foundations, namely Care, Fairness, Loyalty, Authority, and Purity (Graham et al., 2008), this quasi-experimental study aims to understand how certain online public messages structured through different moral framings affect distinct emotions. We explored with a sample of adult participants (N=306, F=58.5%) the different emotional responses after the presentation of posts on immigrants' reception in Italy, simulating interactions in an online context through three different framings: the first focused on the safety, the second on the relevance of help, and a neutral message. The results confirm distinct emotional responses according to different frames and within individual moral systems and political orientation. Keywords: Toxic emotions, prosocial emotions, Moral Frame, Social Networks, Ethical Com-munication, Moral Foundations
Different sulphation degree and biological performance of hyaluronic acid as heparin-like molecule
No full textHyaluronic acid was sulphated and seven derivatives, containing a different number of sulphated groups per disaccharide unit were prepared (HyalS(x) where x can be 1, 2, 2.5, 3,3.5, 3.8, 4).
The behaviour of the sulphated hyaluronic acids was studied at different pH's by using several thermodynamic and spectroscopic techniques. The ability of these macromolecules to form Cu2+ complexes in aqueous solution was also investigated.
The sulphated hyaluronic acids were studied as heparin-like molecules, thus coagulation and angiogenesis in-vitro tests were performed. The influence of the degree of sulphation on the biological activity is well documented
Heterotypic interaction of fibroblasts and endothelial cells on restricted area
No full textThe polysaccharide hyaluronic acid (Hyal) was photoimmobilized on glass surfaces to obtain a pattern with squares and rectangles of different dimensions and chemistry. The microstructured surfaces were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Attenuated Total Reflection Infrared Spectroscopy (ATR FT-IR), and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Surface analysis revealed the presence of a pattern consisting of alternating glass and Hyal microstructures whose dimensions decreased from the center to the edge of the sample. The behavior of Human Coronary Artery Endothelial Cells (HCAEC) and human tumoral dermal fibroblasts (C54) was studied on these micropatterned surfaces. Neither HCAEC nor C54 adhered to the immobilized Hyal but both adapted their shape to the different sizes of the glass squares and rectangles. The number of adherent HCAEC and C54 depended on the dimensions of both the glass domains and the nuclei of the cells. Co-cultured C54 on HCAEC patterned surfaces showed a heterotypic cell-cell interaction in the same chemical and topographic domain for the first time. In comparison to other techniques for patterning two different cell types, our approach was non cytotoxic and allowed arbitrary geometric patterns to form on different biocompatible substrata
Biological performance of two materials based on sulfated hyaluronic acid and polyurethane
No full textPolyurethane bound with sulfated hyaluronic acid was synthesized by two different chemical routes. Both the
materials obtained consist of a hydrophilic component, sulfated hyaluronic acid (HyalS3.5), and a hydrophobic
component, polyurethane (PU). In the material named Puhmdi, the HyalS3.5 was cross-linked to the PU chains
via hexamethylene diisocyanate (HMDI) while in that named Pubrac, the binding of HyalS3.5 to the PU chains
occurred only through a few carboxy groups via N,N'-dicyclohexylcarbodiimide (DCC) and bromoacetic acid.
The surface characteristics of the polymers were investigated by ATR FT-IR spectroscopy while the surface
morphology was analyzed by scanning electron microscopy.
There was a signi®cant difference between the surface characteristics of the ®lms in dry and hydrated
environments. In both materials the hydrophilic component (HyalS3.5) migrates from the bulk to the surface,
thus minimizing the surface free energy of the polymer when exposed to the hydrated environment. The
different biological behavior of the two materials was demonstrated with the thrombin time test and platelet
adhesion test. Pubrac inhibits the coagulation process while Puhmdi does not
Porous multi-layered composite hydrogel as cell substrate for in vitro culture of chondrocytes
No full textA porous multi-layered composite hydrogel (MSC), made of poly(vinyl alcohol) (PVA) and hydroxyapatite (HA), suitable as substitute for damaged cartilage, has been modified by the production of pores and its cytocompatibility and ability to prevent chondrocyte dedifferentiation in in vitro cell culture systems have been evaluated. Pores resulted homogeneously distributed on all the hydrogel surface and bulk. The material was not able to compromise cell viability, proliferation and structure of both NIH3T3 mouse fibroblasts and human chondrocytes (HC), supported HC colonization and showed a good ability to stimulate the production of hyaline extracellular matrix (ECM)
Immobilisation of sulphatede hyaluronan for improved biocompatibility
No full textHyaluronan (Hyal) was modified by the insertion of sulphate to hydroxyl groups. A series of heparin-like compounds with controllable properties was obtained. The physicochemical and biological behaviours of all these sulphated hyaluronan acids (HyalSx) and their complexes with heavy metal ions (Cu2+ and Zn2+) were investigated. HyalS, derivatives showed a good anticoagulant activity and low platelet aggregation which increased with increasing degree of sulphation. Moreover HyalSx and their Cu2+ complexes were demonstrated to favour the growth of human endothelial cells. However, the utilisation of HyalSx as a material is hindered by its high solubility in physiological solution. Our approach to improve its stability was directed to the synthesis of new HyalSx-based hydrogels and on the preparation of new biocompatible polymeric surfaces obtained through covalent photoimmobilisation of HyalSx. The reaction of primary ovine chondrocytes and B10D2 endothelial cells was studied on both matrices in terms of cell number, F-actin and CD44 receptor immunostaining. Analysis of cell movement showed that the cells respond to HyalSx showing good adhesion and spreading. These results suggest that HyalSx containing materials could be used as biomaterials to aid cartilage repair and vessel endothelisation
- …
