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POS0478 TOPICAL CALCIUM CHELATORS FOR TARGETING CUTANEOUS CALCIFICATION: PRECLINICAL EVIDENCE OF EFFICACY. Ann Rheum Dis 2022. [DOI: 10.1136/annrheumdis-2022-eular.2313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BackgroundCutis calcinosis, defined as sub-epidermal deposition of calcium salts, is a painful, disabling, disfiguring, problem in 20-40% of patients with systemic sclerosis. Its pathogenesis remains poorly understood and currently there is no effective disease-modifying pharmacotherapy. One potential strategy is topical application of calcium chelating agents, able to penetrate the epidermal barrier and dissolve subcutaneous calcinotic deposits in situ. To date, the only compound reported for this application has been sodium thiosulfate (STS), with often-contradictory results.ObjectivesTo test the hypothesis, in pre-clinical studies, that polycarboxylic acids can induce calcium dissolution without skin toxicity, with the long-term aim of developing an effective topical treatment for cutis calcinosis.MethodsWe compared the metal ion-chelating agents citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) - polycarboxylic acids with well-characterised chelation profiles – to STS for their ability to chelate calcium, without inducing cytotoxicity or inflammation (pro-inflammatory cytokine expression and release), using in vitro 2D (keratinocyte [HaCaT]; fibroblast ([HCA2]) and recombinant human epidermal (RHE) models. The resultant data was subsequently used to predict therapeutic concentrations for assessment in a validated skin irritation model (SkinEthicTM; Episkin SA) and to assay maximal percutaneous absorption. At relative dermal concentrations, the dissolution performance of each chelator was further assessed using two different models of calcinosis: 1) pharmaceutical dissolution of a hydroxyapatite (HAp) tablet (1) and; 2) dissolution of a calcified extracellular matrix laid down by mineralising SaOS2 in vitro monolayer culture (2).ResultsIncubation with CA, EDTA and STS induced cytotoxicity in both in vitro cell lines studied at concentrations of >10 mM; only EDTA (10 mM) resulted in inflammatory cytokine release (IL8) from cells at these higher concentrations (cf positive control, Lipopolysaccharide 10 mg/mL). When applied topically to RHE models as near-saturated solutions, none of the chelators were categorised as skin irritants. Due to differences in their relative aqueous solubility, higher concentrations of CA (1600 mM) and STS (1200 mM) could be delivered through the RHE model than EDTA (200 mM). Using a simple linear regression model, the rate of compound absorption was: CA, 0.43 ± 0.05; STS, 0.26 ± 0.03 and; EDTA, 0.05 ± 0.01 g/L/hr. At each time-point, the cumulative concentration of compound in the receptor media was CA > STS > EDTA. Incubation with chelators had no effect on the integrity of the RHE by standard histology. Based on the rate of percutaneous absorption, the dissolution performance of each chelator was tested at relative dermal concentrations for phosphate dissolution (nmoles) of HAp (CA, 9.61 ±0.97; EDTA, 5.38 ± 0.28; 3.78 ± 0.58) and in the calcified in vitro model (Figure 1; CA, 3285 ± 105, STS, 947 ± 95, EDTA, 1174 ± 89), showing the superiority of CA in both model systems.Figure 1.Dissolution of a calcified extracellular matrix by citric acidConclusionOverall, this study highlights the promise of polycarboxylic acids, particularly CA, to target subcutaneous calcification, which are neither toxic nor inflammatory to the skin. Specifically, we have identified CA as a potentially more efficacious alternative to STS for the topical treatment of cutis calcinosis.References[1]Fei F, Gallas A, Chang YC, Rao Y, Hunter AC, Winpenny REP, Herrick AL, Lockyer NP, Blanford CF. 2017. Quartz crystal microbalance assay of clinical calcinosis samples and their synthetic models differentiates the efficacy of chelation-based treatments. ACS Appl Mater Interfaces, 9(33):27544-27552[2]Wang QG, Wimpenny I, Dey RE, Zhong X, Youle PJ, Downes S, Watts DC, Budd PM, Hoyland JA, Gough JE. 2018. The unique calcium chelation property of poly(vinyl phosphonic acid-co-acrylic acid) and effects on osteogenesis in vitro. J Biomed Mater Res Part A 2018:106A:168–179Disclosure of InterestsKyle Burgess: None declared, Richard Winpenny: None declared, Alberto Saiani: None declared, Ariane Herrick Speakers bureau: Janssen, Consultant of: Arena, Boehringer-Ingelheim, Camurus, CSL-Behring, Gesynta, Grant/research support from: Gesynta, Rachel Watson Consultant of: NAOS, AbbVie, Grant/research support from: Walgreens Alliance Boots.
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Local spin density in the Cr7Ni antiferromagnetic molecular ring and 53Cr-NMR. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:406002. [PMID: 22971620 DOI: 10.1088/0953-8984/24/40/406002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present (53)Cr-NMR spectra collected at low temperature in a single crystal of the heterometallic antiferromagnetic (AF) ring Cr(7)Ni in the S = 1/2 ground state with the aim of establishing the distribution of the local electronic moment in the ring. Due to the poor S/N we observed only one signal which is ascribed to three almost equivalent (53)Cr nuclei in the ring. The calculated spin density in Cr(7)Ni in the ground state, with the applied magnetic field both parallel and perpendicular to the plane of the ring, turns out to be AF staggered with the greatest component of the local spin <s> for the Cr(3+) ions next to the Ni(2+) ion. The (53)Cr-NMR frequency was found to be in good agreement with the local spin density calculated theoretically by assuming a core polarization field of H(cp) = - 11 T/μ(B) for both orientations, close to the value found previously in Cr(7)Cd. The observed orientation dependence of the local spin moments is well reproduced by the theoretical calculation and evidences the importance of single-ion and dipolar anisotropies.
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Finite size effects in a quantum chain of antiferromagnetically coupled spins 3/2. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311096292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
We have studied magnetization of graphene nanocrystals obtained by sonic exfoliation of graphite. No ferromagnetism is detected at any temperature down to 2 K. Neither do we find strong paramagnetism expected due to the massive amount of edge defects. Rather, graphene is strongly diamagnetic, similar to graphite. Our nanocrystals exhibit only a weak paramagnetic contribution noticeable below 50 K. The measurements yield a single species of defects responsible for the paramagnetism, with approximately one magnetic moment per typical graphene crystallite.
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Abstract
Two polymetallic iron(III) complexes 1 and 2 have been synthesised from the known corrosion inhibitor 3-(4-methylbenzoyl)-propionic acid HL1 and their crystal structures determined. Coordination geometries extracted from these structures have been used as the basis for molecular modelling onto idealised iron(III) oxide surfaces as an aid to understanding the efficacy of inhibitors of the 4-keto acid type. The proposed mode of action involves 1,3-bridging didentate coordination of the carboxylate function of L1 to two FeIII ions, hydrogen-bond formation between the 4-keto group of L1 and a bridging surface hydroxy group, as well as close packing of the aromatic end groups, which should generate a hydrophobic barrier on the surface. Adsorption isotherm experiments have been used to compare the strengths of binding of related carboxylic acids onto iron(III) oxide surfaces and indicate that the presence of the 4-keto function leads to the formation of significantly more stable surface complexes.
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Abstract
The synthesis and structural characterisation of a series of cobalt and nickel cages are reported. Eight of these structures contain a [M10(mu3-OH)6(eta2, mu3-xhp),(eta2, mu2-O2CR)6]2+ core (where M = Co or Ni; xhp = 6-chloro- or 6-methyl-2-pyridonate: R = Me, Ph, CHMe2, CH2Cl, CHPh2 or CMe3), where the ten metal atoms describe a centred-tricapped-trigonal prism (ttp). The cage contains six hydroxide ligands around the central metal, and the exterior is coated with pyridonate and carboxylate ligands. For four of the cages additional metal centres are found attached to the upper and/or lower triangular faces of the trigonal prism, generating dodeca- and undecanuclear cages. Three further cages are reported that contain a metal core based on an incomplete centred-tetraicosahedron. These cages involve trimethylacetate as a ligand in company with either 6-methyl-2-pyridonate or 6-chloro-2-pyridonate. Comparison of these latter structures with the trigonal prisms reveal that they can be described as a pentacapped-trigonal prism missing one edge. Magnetic studies of three of the nickel cages with trigonal prismatic cores show spin ground states of S = 8, 4 and 2 for Ni12, Ni11 and Ni10 cages, respectively.
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The detection of Epstein-Barr virus in hairy cell leukemia cells by in situ hybridization. THE AMERICAN JOURNAL OF PATHOLOGY 1990; 136:717-23. [PMID: 2156435 PMCID: PMC1877477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Epstein-Barr virus (EBV) has been implicated in the pathogenesis of several B-cell lymphoid proliferations. Because patients with hairy cell leukemia (HCL) have a high incidence of seropositivity for EBV antigens, we studied the cells of HCL for evidence of EBV infection using in situ hybridization techniques. EBV mRNA was detected in the tumor cells in four of six cases using a radiolabeled RNA probe. Confirmatory serologic data were available in three cases in which the viral DNA was detected and in one negative case. Our results suggest that EBV infection may have a pathogenetic role in this disorder.
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MESH Headings
- Adult
- Antigens, Viral/immunology
- DNA, Viral/genetics
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/immunology
- Herpesvirus 4, Human/isolation & purification
- Humans
- Leukemia, Hairy Cell/immunology
- Leukemia, Hairy Cell/microbiology
- Leukemia, Hairy Cell/pathology
- Male
- Microscopy, Electron
- Middle Aged
- Nucleic Acid Hybridization
- RNA, Messenger/genetics
- RNA, Viral/genetics
- Spleen/microbiology
- Spleen/pathology
- Spleen/ultrastructure
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