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155 results on '"Walton, James. W."'

4. Biotinylated selenocyanates: Potent and selective cytostatic agents

Author

Universidad de Sevilla. Departamento de Química orgánica, Ministerio de Ciencia e Innovación (MICIN). España, Junta de Andalucía, Republic of Serbia Government, Roldán Peña, Jesús Miguel, Puerta, Adrián, Dinić, Jelena, Jovanović Stojanov, Sofija, González-Bakker, Aday, Hicke, Francisco J., Mishra, Atreyee, Piyasaengthong, Akkharadet, Maya Castilla, Inés, Walton, James W., Pešić, Milica, Padrón, José M., Fernández-Bolaños Guzmán, José María, López López, Óscar, Universidad de Sevilla. Departamento de Química orgánica, Ministerio de Ciencia e Innovación (MICIN). España, Junta de Andalucía, Republic of Serbia Government, Roldán Peña, Jesús Miguel, Puerta, Adrián, Dinić, Jelena, Jovanović Stojanov, Sofija, González-Bakker, Aday, Hicke, Francisco J., Mishra, Atreyee, Piyasaengthong, Akkharadet, Maya Castilla, Inés, Walton, James W., Pešić, Milica, Padrón, José M., Fernández-Bolaños Guzmán, José María, and López López, Óscar

Abstract

Most of the currently available cytotoxic agents for tackling cancer are devoid of selectivity, thus causing severe side-effects. This situation stimulated us to develop new antiproliferative agents with enhanced affinity towards tumour cells. We focused our attention on novel chalcogen-containing compounds (thiosemicarbazones, disulfides, selenoureas, thio- and selenocyanates), and particularly on selenium derivatives, as it has been documented that this kind of compounds might act as prodrugs releasing selenium-based reactive species on tumour cells. Particularly interesting in terms of potency and selectivity was a pharmacophore comprised by a selenocyanato-alkyl fragment connected to a p-phenylenediamine residue, where the nature of the second amino moiety (free, Boc-protected, enamine-protected) provided a wide variety of antiproliferative activities, ranging from the low micromolar to the nanomolar values. The optimized structure was in turn conjugated through a peptide linkage with biotin (vitamin B7), a cellular growth promoter, whose receptor is overexpressed in numerous cancer cells; the purpose was to develop a selective vector towards malignant cells. Such biotinylated derivative behaved as a very strong antiproliferative agent, achieving GI50 values in the low nM range for most of the tested cancer cells; moreover, it was featured with an outstanding selectivity, with GI50 > 100 µM against human fibroblasts. Mechanistic studies on the mode of inhibition of the biotinylated selenocyanate revealed (Annexin-V assay) a remarkable increase in the number of apoptotic cells compared to the control experiment; moreover, depolarization of the mitochondrial membrane was detected by flow cytometry analysis, and with fluorescent microscopy, what supports the apoptotic cell death. Prior to the apoptotic events, cytostatic effects were observed against SW1573 cells using label-free cell-living imaging; therefore, tumour cell division was prevented. Multidrug resistan

Published
2023

15. Enolate SNAr of unactivated arenes via [(η6-arene)RuCp]+ intermediates.

Author

Williams, Luke J., Bhonoah, Yunas, and Walton, James W.

Subjects
AROMATIC compounds, ARYL halides, NITROAROMATIC compounds, ARYL group, ABILITY grouping (Education), HALIDES
Abstract

A series of complexes of the general formula [(η6-arene)RuCp][PF6] (where arene = aryl halides or nitroarenes) were synthesised and the arene ring was found to be reactive towards an intermolecular nucleophilic aromatic substitution (SNAr) reaction with a series of cyclic 1,3-diones. Competition experiments indicated that leaving group ability of the aryl halides and nitroarenes went in the order of F ≫; NO2 > Cl > Br. Following SNAr, the arene rings were liberated quantitatively via a rapid photolysis reaction (<15 min). [ABSTRACT FROM AUTHOR]

Published
2022
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18. Health programs in faith-based organizations: are they effective?

Author

DeHaven, Mark J., Hunter, Irby B., Wilder, Laura, Walton, James W., and Berry, Jarett

Subjects
Health promotion -- Research, Government, Health care industry
Abstract

Objectives. We examined the published literature on health programs in faith-based organizations to determine the effectiveness of these programs. Methods. We conducted a systematic literature review of articles describing faith-based health activities. Articles (n =386) were screened for eligibility (n = 105), whether a faith-based health program was described (n = 53), and whether program effects were reported (28). Results. Most programs focused on primary prevention (50.9%), general health maintenance (25.5%), cardiovascular health (20.7%), or cancer (18.9%). Significant effects reported included reductions in cholesterol and blood pressure levels, weight, and disease symptoms and increases in the use of mammography and breast self-examination. Conclusions. Faith-based programs can improve health outcomes. Means are needed for increasing the frequency with which such programs are evaluated and the results of these evaluations are disseminated.

Published
2004

20. FRET based ratiometric switch for selective sensing of Al3+ with bio-imaging in human peripheral blood mononuclear cells.

Author

Das, Sangita, Pratim Das, Partha, Walton, James W., Ghoshal, Kakali, Patra, Lakshman, and Bhattacharyya, Maitree

Subjects
FLUORESCENT probes, CHEMORECEPTORS, FLUORESCENCE resonance energy transfer, BLOOD cells, TRANSITION metal ions, BIOLOGICAL systems, CELL permeability, ALUMINUM foam
Abstract

In this work, a triphenylamine and rhodamine-B (donor–acceptor) hybrid switch (TPRH) was rationally designed, synthesised and characterised as a novel fluorescence resonance energy transfer (FRET) ratiometric fluorescent chemosensor for specific sensing of Al3+ over other important metal ions in mixed aqueous solution. We proposed that the sensor in hand (TPRH) is non-toxic and can be successfully employed to detect the Al3+ ion in human peripheral blood mononuclear cells (PBMCs), showing intracellular 'FRET-ON' mechanism. The orientation of the probe was designed in such a way that the fluorescence (or Förster) resonance energy transfer (FRET) proceeded from the 'donor moiety' triphenylamine to the 'accepter moiety' rhodamine-B. This fluorescent probe was found to be highly selective towards Al3+ over other important guest metal ions, including Fe3+ and Cr3+. Considering the adverse effects of Al3+ ions on human health and also on the environment, the development of sensitive and specific tools for the detection of Al3+ ions is of great value. The limit of detection (LOD) of TPRH was found to be in the order of 10−8 M. The TPRH–Al3+ complex showed reversible binding with demetallation in the presence of EDTA. In accordance with this reversibility, the fluorescence output at 576 nm from two active chemical inputs, namely, Al3+ and EDTA, followed a truth table of an INHIBIT logic gate. Moreover, cytotoxic studies found that the probe was safe to use in a biological system with good cell membrane permeability. More importantly, the bio-imaging of living human peripheral blood mononuclear cells (PBMCs) showed that TPRH could be used as an effective fluorescent probe for a prominent ratiometric in vitro detection of the transition trivalent metal ion Al3+. We evidenced a significant (p < 0.05) shift from blue to red fluorescence when Al3+ was added to the cell suspension, thus proving TPRH as a good candidate to detect intracellular Al3+. [ABSTRACT FROM AUTHOR]

Published
2021
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27. ChemInform Abstract: EuroTracker Dyes: Design, Synthesis, Structure and Photophysical Properties of Very Bright Europium Complexes and Their Use in Bioassays and Cellular Optical Imaging

Author

Butler, Stephen J., primary, Delbianco, Martina, additional, Lamarque, Laurent, additional, McMahon, Brian K., additional, Neil, Emily R., additional, Pal, Robert, additional, Parker, David, additional, Walton, James W., additional, and Zwier, Jurriaan M., additional

Published
2015
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30. Anticancer RuII and RhIII Piano-Stool Complexes that are Histone Deacetylase Inhibitors.

Author

Cross, Jasmine M., Blower, Tim R., Gallagher, Natalie, Gill, Jason H., Rockley, Kimberly L., and Walton, James W.

Subjects
ANTINEOPLASTIC agents, RUTHENIUM compounds, HISTONE deacetylase inhibitors, HYDROXAMIC acid derivatives, NON-small-cell lung carcinoma, CANCER treatment
Abstract

The first examples of RuII and RhIII piano-stool complex histone deacetylase (HDAC) inhibitors are presented. The novel complexes have antiproliferative activity against H460 non-small-cell lung carcinoma cells that is comparable to the clinically used HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Strong evidence for HDAC inhibition as a primary mechanism of action is provided. The complexes reported here represent an important step towards the design of highly active and selective HDAC inhibitors. [ABSTRACT FROM AUTHOR]

Published
2016
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31. Comparative Analysis of Conjugated Alkynyl Chromophore–Triazacyclononane Ligands for Sensitized Emission of Europium and Terbium

Author

Soulié, Marine, primary, Latzko, Frédéric, additional, Bourrier, Emmanuel, additional, Placide, Virginie, additional, Butler, Stephen J., additional, Pal, Robert, additional, Walton, James W., additional, Baldeck, Patrice L., additional, Le Guennic, Boris, additional, Andraud, Chantal, additional, Zwier, Jurriaan M., additional, Lamarque, Laurent, additional, Parker, David, additional, and Maury, Olivier, additional

Published
2014
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34. Isostructural series of nine-coordinate chiral lanthanide complexes based on triazacyclononane

Author

Walton, James W., Carr, Rachel, Evans, Nicholas H., Funk, Alexander M., Kenwright, Alan M., Parker, David, Yufit, Dmitry S., Botta, Mauro, De Pinto, Sara, Wong, Ka-Leung, Walton, James W., Carr, Rachel, Evans, Nicholas H., Funk, Alexander M., Kenwright, Alan M., Parker, David, Yufit, Dmitry S., Botta, Mauro, De Pinto, Sara, and Wong, Ka-Leung

Abstract

Nonadentate ligands based on triazacyclononane incorporating pyridyl-2-phosphinate groups form an isostructural series of complexes with Ln ions in the solid state and in solution. The Ln ion is effectively shielded from the solvent environment. Crystal structures reveal a rigid C-3-symmetric tricapped trigonal-prismatic coordination geometry that is maintained in solution for the methyl and phenylphosphinate series, as shown by multinuclear NMR analysis. Variable-temperature measurements of the field dependence of the water proton relaxivity in gadolinium complexes indicate that these systems exclude solvent from the primary coordination environment and minimize the second sphere of solvation. The electronic relaxation time for the gadolinium methylphosphinate complex has been estimated to be 550 (+/-150) ps by EPR and NMR methods, compared to values of around 0.30-0.05 ps for the terbium-ytterbium series, deduced by analyzing the field dependence (4.7-16.5 T) of the P-31 NMR longitudinal relaxation times. Values are compared with analogous azacarboxylate ligand complexes, supporting a key role for donor atom polarizability in determining the electronic relaxation. Spectral emission behavior in solution of samarium, europium, terbium, and dysprosium complexes is compared, and the resolved RRR-Zeta and SSS-Delta complexes show strong circularly polarized luminescence. The molecular quadratic hyperpolarizability has been measured in solution using hyper-Raleigh light-scattering methods, for the whole series of lanthanide complexes of one ligand. The values of reach a maximum around the center of the series and are not simply dependent on the number of f electrons, suggesting a dominant contribution from the octupolar rather than the dipolar term.

Published
2012

37. Very bright europium complexes that stain cellular mitochondria

Author

Walton, James W., primary, Bourdolle, Adrien, additional, Butler, Stephen J., additional, Soulie, Marine, additional, Delbianco, Martina, additional, McMahon, Brian K., additional, Pal, Robert, additional, Puschmann, Horst, additional, Zwier, Jurriaan M., additional, Lamarque, Laurent, additional, Maury, Olivier, additional, Andraud, Chantal, additional, and Parker, David, additional

Published
2013
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47. Catalytic SNAr of unactivated aryl chlorides.

Author

Walton, James W. and Williams, Jonathan M. J.

Subjects
*ARYL chlorides, *AROMATIC compounds, *NUCLEOPHILIC aromatic photosubstitution
Abstract

We present nucleophilic aromatic substitution of unsubstituted aryl chlorides via a mechanism that is catalytic in [CpRu(p-cymene)]PF6 and involves a Ru(η6-arylchloride) intermediate. From the spectroscopic evidence we infer that arene exchange is the rate limiting step in this process and develop several new Ru(II) complexes that lower the activation barrier to arene exchange. [ABSTRACT FROM AUTHOR]

Published
2015
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48. Catalytic SNAr of unactivated aryl chlorides.

Author

Williams, Jonathan M. J. and Walton, James W.

Subjects
*NUCLEOPHILIC substitution reactions, *ARYL chlorides, *CATALYTIC activity, *ELECTROSPRAY ionization mass spectrometry, *CHLOROTOLUENES, AROMATIC compound reactivity
Abstract

We present nucleophilic aromatic substitution of unsubstituted aryl chlorides via a mechanism that is catalytic in [CpRu(p-cymene)]PF6 and involves a Ru(η6-arylchloride) intermediate. From the spectroscopic evidence we infer that arene exchange is the rate limiting step in this process and develop several new Ru(ii) complexes that lower the activation barrier to arene exchange. [ABSTRACT FROM AUTHOR]

Published
2015
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49. Diccionario bilingüe Muinane-Español, Español-Muinane

Author

Pakky, Clementina, Maxwell, Michael B., Walton, James W., Walton, Janice P., Pakky, Clementina, Maxwell, Michael B., Walton, James W., and Walton, Janice P.

Abstract

http://www.sil.org/resources/archives/18784

Published
1997

50. Invited Commentaries

Author

Clancy, Carolyn M., primary, Walton, James W., additional, Berry, Jarett D., additional, and Dehaven, Mark J., additional

Published
2002
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