1,721,015 research outputs found
The importance of Structural and Functional Analysis of Extracts in Plants
Full text linkPlants 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
Full text linkNatural 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
Full text linkThis 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
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
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)
Hyaluronan derivatives: chemical modification and biochemical applications
No full textSeven sulphated hyaluronic acid (HA) derivatives, with a general formula HyalS(x) (x = 1, 2, 2.5, 3, 3.5, 3.8, and 4), were synthesised. Coagulation tests performed on these compounds yielded promising results for HyalS(2.5) to HyalS(4). The relationship of the anticoagulant activity of HyalS to chain length was also evaluated. HyalS(x) cytotoxicity and cytocompatibility were assessed by a direct contact method using L929 fibroblasts and human endothelial cells. Tests of HyalS(x) susceptibility to enzymatic degradation showed that the introduction of sulphate along the hyaluronic acid chain renders the macromolecules resistant to enzymatic digestion. The interaction of HyalS(x) derivatives with platelets was determined by platelet aggregation, activation, and von Willebrand Factor-dependent agglutination. Moreover, the ability of HyalS to form complexes with metallic ions such as Cu(II) and Zn(II) was evaluated together with the ability of these complexes to favour cell adhesion and stimulate cell migration. Various HyalS derivatives were immobilised by different chemical routes on the surface of polymeric materials and the physico-chemical and biological characteristics of the modified materials were studied. Lastly the therapeutic potential of Hyal hydrogels generated by a cross-linking reaction and then sulphated to improve their haemocompatibility, were evaluated in an animal model of articular inflammation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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