ORCID Profile
0000-0002-3792-2653
Current Organisations
University of Hawaii at Manoa
,
Universidade de Lisboa Faculdade de Ciências
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Publisher: Elsevier BV
Date: 04-2004
Publisher: Springer Science and Business Media LLC
Date: 1999
Abstract: Ovine, caprine and bovine endothelial cells were grown in vitro and challenged with Clostridium perfringens type D epsilon toxin to compare their susceptibility to this toxin. Madin Darby canine kidney (MDCK) cells, which are known to be susceptible to epsilon toxin, were used as a positive control. No morphological alterations were observed in any of the endothelial cell cultures tested, even after challenging with doses as high as 1200 MLD50/ml of epsilon toxin. MDCK cells showed contour rounding and nuclear condensation as early as 30 min after exposure to 100 MLD50/ml of epsilon toxin and after 60 min of exposure to 12.5 MLD50/ml of the same toxin. All the MDCK cells were dead after 3 h of exposure to all concentrations of epsilon toxin. The results indicate that ovine, caprine and bovine endothelial cells are not morphologically responsive to the action of epsilon toxin in vitro.
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.BIOMATERIALS.2011.05.083
Abstract: This paper reports a clear elucidation of the pathway for the cellular delivery of layered double hydroxide (LDH) nanoparticles intercalated with anti-restenotic low molecular weight heparin (LMWH). Cellular uptake of LMWH-LDH conjugates into cultured rat vascular smooth muscle cells (SMCs) measured via flow cytometry was more than ten times greater than that of LMWH alone. Confocal and transmission electron microscopy showed LMWH-LDH conjugates taken up by endosomes, then released into the cytoplasm. We propose that LMWH-LDH is taken up via a unique 'modified endocytic' pathway, whereby the conjugate is internalized by SMCs in early endosomes, sorted in late endosomes, and quickly released from late endosomes/lysosomes, avoiding degradation. Treatment of cells with LMWH-LDH conjugates suppressed the activation of ERK1/2 in response to foetal calf serum (FCS) for up to 24h, unlike unconjugated LMWH which had no significant effect at 24h. Improved understanding of the intracellular pathway of LMWH-LDH nanohybrids in SMC will allow for refinement of design for LDH nanomedicine applications.
Publisher: Elsevier BV
Date: 02-0008
DOI: 10.1016/J.JCIS.2017.10.069
Abstract: The mounting interest in layered double hydroxide (LDH) nanoparticles as drug carriers and bio-imaging contrast agents makes biosafety evaluation of LDH essential. Considering the important role of blood circulation in bio-distribution of nanoparticles, the present work evaluated the impact of MgAl-LDHs on key components of the circulatory system, including vascular cells (vascular smooth muscle cells (SMCs) and endothelial cells (HUVECs)), red blood cells (RBCs), and complement activation. The results showed that LDH had no effects on SMCs and HUVECs at concentrations up to 500 and 10 µg/mL respectively, in terms of cell proliferation and viability. LDH (10 µg/mL) did not change either the migration distance or the number of migrating SMCs in culture. Moreover, LDH (400 µg/mL) had a negligible effect on RBCs' lysis, and there was no significant increase in levels of complement activation product, C5a, in the presence of LDH (20 or 200 µg/mL). The low toxicity for vascular cells and blood cells combined with low immunogenicity sheds a light on the biosafety of LDH nanoparticles, and encourages further studies into their biomedical applications.
Publisher: Oxford University Press (OUP)
Date: 04-2003
DOI: 10.1016/S0008-6363(02)00832-5
Abstract: Our previous studies showed that the pleiotropic cytokine leukaemia inhibitory factor (LIF) inhibits the de novo formation of experimental atherosclerotic lesions. The present study examined whether LIF also inhibits progression of pre-existing atheroma. Balloon angioplasty was performed on the right carotid arteries of 18 rabbits immediately before placing animals on a cholesterol-enriched diet. After 4 weeks, at which time the intima:media ratio (I:M) was 0.99+/-0.12 (n=6), osmotic minipumps containing LIF (n=6) or saline control (n=6) were inserted into the peritoneal cavity of each of the remaining rabbits for a further 4 weeks. Arteries were then harvested for analysis. Continuous administration of LIF for the final 4 weeks of an 8-week cholesterol-enriched diet completely inhibited lesion progression in injured carotid arteries (I:M 1.05+/-0.16) compared with the saline-treated group at 8 weeks (1.62+/-0.13 P<0.05). Similarly in contralateral uninjured carotid arteries, LIF treatment prevented an increase in I:M from a baseline of 0.11+/-0.01 at 4 weeks to 0.15+/-0.02 at 8 weeks compared with 0.40+/-0.04 for the saline-treated group at 8 weeks (P<0.05). LIF reduced the number of macrophages in the neointima of uninjured arteries, but had no effect on the cellular composition of injured arteries. LIF treatment normalised smooth muscle-dependent vasoreactivity to phenylephrine and sodium nitroprusside in both injured and uninjured arteries. Expression and activity of inducible nitric oxide synthase (iNOS) were up-regulated in response to hypercholesterolemia with levels further increased following endothelial denudation. With LIF treatment, iNOS expression was increased in uninjured arteries but marginally reduced in injured arteries. LIF receptors were expressed in both uninjured and injured arteries, with LIF treatment having no significant effect on expression levels. LIF prevents progression of pre-formed atherosclerotic plaques, affecting lesion size and vascular reactivity. LIF treatment has differential effects within the artery wall, depending on the presence or absence of de-endothelialisation injury.
Publisher: American Chemical Society (ACS)
Date: 20-05-2008
DOI: 10.1021/CM703602T
Publisher: MDPI AG
Date: 18-02-2020
Abstract: The juveniles of gnathiid isopods are one of the most common fish ectoparasites in marine habitats and cause deleterious effects on fish by feeding on host blood and lymph. Reef fishes tend to engage in cooperative interactions with cleaning organisms to reduce their ectoparasite load. Ocean acidification (OA) pose multiple threats to marine life. Recently, OA was found to disrupt cleaner fish behaviour in mutualistic cleaning interactions. However, the potential effects of ocean acidification on this common ectoparasite remains unknown. Here, we test if exposure to an acidification scenario predicted by IPCC to the end of the century (RCP 8.5 – 980 μatm pCO2) affects gnathiid survival. Our results show that ocean acidification did not have any effects on gnathiid survival rate during all three juvenile life stages. Thus, we advocate that the need for cleaning interactions will persist in potentially acidified coral reefs. Nevertheless, to better understand gnathiid resilience to ocean acidification, future studies are needed to evaluate ocean acidification impacts on gnathiid reproduction and physiology as well as host-parasite interactions.
Publisher: Wiley
Date: 12-07-2012
Abstract: Targeted local delivery of a nanoparticle-based, antibody-targeted, and low molecular weight heparin (LMWH) delivery system successfully reduces restenosis and thrombus formation in an animal model. An antibody recognizing cross-linked fibrin (XLF) D-dimer is successfully conjugated to layered double hydroxide nanoparticles. Use of the anti-XLF-conjugated LMWH-carrying layered double hydroxide nanoparticles shows successful targeting of the nanoparticles (red) to the injured artery wall (green), resulting in decreased neointimal thickening and thrombus formation.
Publisher: Elsevier BV
Date: 10-2008
Publisher: Elsevier BV
Date: 07-1999
DOI: 10.1016/S0021-9150(99)00019-2
Abstract: Previous studies from this laboratory have shown that degradation of heparan sulphate proteoglycan by both living macrophages and macrophage lysosomal heparanase induces phenotypic change of vascular smooth muscle cells (SMC) from a high volume fraction of myofilaments (V(v)myo) to a low V(v)myo [C bell et al. Exp Cell Res 1992 200: 156-167]. The aim of this study was to determine whether matrix metalloproteinase (MMP) activity is also involved in the induction of SMC phenotypic change by macrophages. A specific inhibitor of MMPs (BB94) was able to block macrophage-induced SMC phenotypic change and subsequent DNA synthesis in freshly dispersed SMC seeded in primary culture at confluent density. The inhibitor did not block these SMC changes when SMC were seeded at low density without macrophages nor did it block heparanase activity directly. We also determined whether heparanase and MMP activities are upregulated together in vivo. Artery homogenates were analysed in a heparanase enzyme assay and for MMPs using zymograms. Increased heparanase activity was observed 3-14 days following balloon catheter injury of rabbit carotid arteries, and returned to control levels 6 weeks after injury. Active MMP2 was induced with heparanase after injury. MMP9 induction was also apparent 6 h after injury. Immunohistology on sections of these arteries showed the presence of MMPI1, 2, 3 and 9 with these MMPs being strongly induced in the intima 7 days after balloon catheter injury. Both heparanase and MMP activities were also present in human end-stage complex lesions from coronary arteries, carotid endarterectomies and abdominal aortic aneurysms. Because MMPs and heparanase are expressed at the same time, it is possible that MMPs facilitate heparanase activity in promotion of phenotypic modulation of SMC in vivo during neointimal thickening following injury and in atherosclerotic lesions.
Publisher: Wiley
Date: 02-1995
Location: Portugal
Location: Portugal
Location: Portugal
No related grants have been discovered for Anita Thomas.