141 research outputs found
The importance of Structural and Functional Analysis of Extracts in Plants
No full textPlants and their extracts have traditionally been used against various pathologies and in some regions are the only therapeutic source for the treatment and prevention of many chronic diseases [...
Bioactive Natural Compounds with Antiplatelet and Anticoagulant Activity and Their Potential Role in the Treatment of Thrombotic Disorders
No full textNatural anticoagulant drugs can be obtained from plants, rich in secondary bioactive metabolites which, in addition to being effective antioxidants, also possess anticoagulant and antiplatelet properties and, for this reason, can be excellent candidates for the treatment of thrombotic diseases. This review reports an overview of the hemostatic process and thrombotic disorders together with data on plants, more and less common from around the world, containing bioactive compounds characterized by antiplatelet and anticoagulant activity. The reported literature was obtained from Medline, PubMed, Elsevier, Web of Science, Google Scholar considering only articles in the English language, published in peer-reviewed journals. The number of citations of the articles and the impact factor of the journals were other parameters used to select the scientific papers to be included in the review. The analysis of the literature data selected demonstrates that many plants’ bioactive compounds show antiplatelet and anticoagulant activity that make them potential candidates to be used as new natural compounds able to interfere with both primary and secondary hemostasis. Moreover, they could be used together with anticoagulants currently administered in clinical practice to increase their efficacy and to reduce complications in the treatment of thrombotic disorders
Preliminary In Vitro Cytotoxicity, Mutagenicity and Antitumoral Activity Evaluation of Graphene Flake and Aqueous Graphene Paste
No full textThis study aimed to determine the in vitro cytotoxicity and mutagenicity of graphene flake (GF) and aqueous graphene paste (AGP) in order to evaluate their potential for application as biomaterials. Furthermore, their antitumor activity against adherent and suspended cells, namely, human breast adenocarcinoma cells (MDA-MB-231), and human monocytes from histiocytic lymphoma (U-937), was investigated. The results demonstrated that GF reduced the viability and proliferation of NIH3T3 immortalized murine fibroblasts for concentrations >0.8 µg/mL and incubation times of 48 and 72 h. AGP showed no toxic effects in any of the tested concentrations and incubation times. The same results were obtained for MDA-MB-231 cells. The viability of the U-937 cells was not affected by either GF or AGP. The Ames test showed that GF and AGP were not genotoxic against Salmonella typhimurium strains TA98 and TA100, with and without metabolic activation. The present study demonstrated good in vitro cellular compatibility of GF and AGP and. Among these, AGP was the best material as it did not interfere, at any of the tested concentrations, with cell viability and proliferation for up to 72 h of incubation. In any case, neither material induced alterations to cell morphology and were not mutagenic
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
Braccio da Montone e la distruzione dell'abbazia di S. Maria di Chiaravalle di Fiastra: fatto storico o leggenda?
No full textThe role of Fbg in platelet adhesion to polymeric materials in conditions of psychological stress
No full textThe effect of psychological stress on platelet adhesion to five polymeric materials (polyurethane, polyurethane filled with BaSO4, polyethyleneterephthalate, silicone and low-density polyethylene) was studied. The platelets were obtained from non-stressed and stressed rabbits as platelet-rich plasma (PRP) and, once washed (Pw), were suspended in different media, i.e. in platelet poor plasma (Pw-PPP), in serum (Pw-S) and in Krebs-Ringer solution (Pw-KR). Scanning electron microscopy of platelet adhesion and morphology revealed differences in the platelet activating power of the various materials. The washing procedure and resuspension in PPP generally resulted in an increased number of adherent platelets, compared with the number of platelets adherent to the same material in PRP. However, platelets washed and suspended in Pw-KR or Pw-S showed the same shape distribution as in PRP. When platelets from stressed rabbits were used, there was very strong aggregation and activation of the platelets in both PRP and Pw-PPP, independent of the chemical nature and surface structure of the material. In contrast, in Pw-KR and Pw-S tin which Fbg is absent) a general picture of single, not very modified platelets was observed. Their number and shapes changed according to the nature of the different materials. On the whole, the present results confirm our original hypothesis of a key role of the psychological condition of the blood donor and strongly indicate Fbg as the determinant factor in the pattern of platelet adhesion
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
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
Phosphorylated xanthan gum-Ag(I) complex as antibacterial viscosity enhancer for eye drops formulation
No full textTopical instillation of eye drops represents the treatment of choice for many ocular diseases. Ophthalmic formulations must meet general requirements, i.e. pH, osmolality, transparency and viscosity to ensure adequate retention without inducing irritation and the development of eye infections. We developed a phosphorylated xanthan gum–Ag(I) complex (XGP-Ag) showing pH (pH = 7.1 ± 0.3) and osmolality values (311 ± 2 mOsm/kg) close to that of human tears (pH = 6.5–7.6 and 304 ± 23 mOsm/kg) thanks to the presence of phosphate moieties along the chain. The presence of phosphate groups covalently bound to the XG chains avoids their dispersion in fluid, thus reducing the risk of corneal calcification. 0.02% w/v XGP-Ag solution showed high transparency (higher than 95% along the entire visible range), adequate refractive index (1.334 ± 0.001) and viscosity in the range: γ 1 s-1-10,000 s- 1 (26.4 ± 0.8–2.1 ± 0.4 mPa·s). Its cytotoxicity and capability to hinder bacterial proliferation was also verified
The use of hyaluronan and its sulphated derivative patterned with micrometric scale on glass substrate in melanocyte cell behaviour
No full textSurface microfabrication techniques were widely utilised for the spatial control of in vitro cell behaviour. A photo-immobilisation procedure was utilised to create micropatterned surfaces: four different stripe patterns (100, 50, 25 and 10 mm) of hyaluronan (Hyal) and its sulphated derivative (HyalS) on silanised glass substrate were obtained.
The morphological analysis showed that the surface topography showed regular stripes of 100, 50, 25 and 10 mm wide and ranging from 300nm up to 1 mm in thickness. They reproduced the exact photo-mask pattern: glass stripes alternating with polysaccharide ones. On the contrary, Hyal microstructures showed just a topographic pattern as the glass stripes appeared to be covered by a thin layer of the macromolecule by TOF-SIMS.
Cell adhesion studies demonstrated that melanocytes adhered and oriented within the first 2 h of culture on HyalS microdomains and not on Hyal microstructures where they spread on glass substrate around the patterned area.
Double photo-immobilised samples characterised by a 100 mm stripe pattern of Hyal or HyalS on the top of a continuous layer of the two polysaccharides were also created in order to investigate the effect of the topography on cell behaviour. The obtained results demonstrated that melanocytes adhered on HyalS stripes while on the Hyal micropatterned surfaces they spread on silanised glass substrate around the structured area, resulting in the exclusion of the topographic pattern
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