1
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Rao N, Bala M, Ranganathan N, Anand U, Dhingra S, Costa JC, Weber AM. Trends in the prevalence and social determinants of stunting in India, 2005-2021: findings from three rounds of the National Family Health Survey. BMJ Nutr Prev Health 2023; 6:357-366. [PMID: 38618541 PMCID: PMC11009545 DOI: 10.1136/bmjnph-2023-000648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 11/20/2023] [Indexed: 04/16/2024] Open
Abstract
Objectives To assess social determinants of stunting and the shifts in contributions of socio-demographic factors to national prevalence trends in India between 2005 and 2021. Methods We leveraged data from three rounds of the National Family Health Survey (NFHS-3: 2005-2006, NFHS-4: 2015-2016, NFHS-5: 2019-2021) for 443 038 children under 5 years. Adjusted logistic regression models and a Kitigawa-Oaxaca-Blinder decomposition were deployed to examine how wealth, residence, belonging to a marginalised social group, maternal education and child sex contributed to changes in stunting prevalence. Results The decrease in stunting prevalence was notably slower between NFHS-4 and NFHS-5 (annual average rate of reduction (AARR): 1.33%) than between NFHS-3 and NFHS-4 (AARR: 2.20%). The protective effect of high wealth diminished from 2015 onwards but persisted for high maternal education. However, an intersection of higher household wealth and maternal education mitigated stunting to a greater extent than either factor in isolation. Residence only predicted stunting in 2005-2006 with an urban disadvantage (adjusted OR: 1.18; 95% CI: 1.07 to 1.29). Children from marginalised social groups displayed increased likelihoods of stunting, from 6-16% in 2005-2006 to 11-21% in 2015-2016 and 2020-2021. Being male was associated with 6% and 7% increased odds of stunting in 2015-2016 and 2019-2021, respectively. Increased household wealth (45%) and maternal education (14%) contributed to decreased stunting prevalence between 2005 and 2021. Conclusions Stunting prevalence in India has decreased across social groups. However, social disparities in stunting persist and are exacerbated by intersections of low household wealth, maternal education and being from a marginalised social group. Increased survival must be accompanied by needs-based interventions to support children and mitigate mutually reinforcing sources of inequality.
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Affiliation(s)
- Nirmala Rao
- Faculty of Education, The University of Hong Kong, Hong Kong, Hong Kong
| | - Manya Bala
- Faculty of Education, The University of Hong Kong, Hong Kong, Hong Kong
| | | | - Utkarsh Anand
- School of Economic Sciences, Washington State University, Pullman, Washington, USA
| | | | - Janaina Calu Costa
- International Center for Equity in Health, Federal University of Pelotas, Pelotas, RS, Brazil
| | - Ann M Weber
- University of Nevada Reno, Reno, Nevada, USA
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2
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Ghosh T, Fritz EC, Balakrishnan D, Zhang Z, Vrancken N, Anand U, Zhang H, Loh ND, Xu X, Holsteyns F, Nijhuis CA, Mirsaidov U. Preventing the Capillary-Induced Collapse of Vertical Nanostructures. ACS Appl Mater Interfaces 2022; 14:5537-5544. [PMID: 35040618 DOI: 10.1021/acsami.1c17781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Robust processes to fabricate densely packed high-aspect-ratio (HAR) vertical semiconductor nanostructures are important for applications in microelectronics, energy storage and conversion. One of the main challenges in manufacturing these nanostructures is pattern collapse, which is the damage induced by capillary forces from numerous solution-based processes used during their fabrication. Here, using an array of vertical silicon (Si) nanopillars as test structures, we demonstrate that pattern collapse can be greatly reduced by a solution-phase deposition method to coat the nanopillars with self-assembled monolayers (SAMs). As the main cause for pattern collapse is strong adhesion between the nanopillars, we systematically evaluated SAMs with different surface energy components and identified H-bonding between the surfaces to have the largest contribution to the adhesion. The advantage of the solution-phase deposition method is that it can be implemented before any drying step, which causes patterns to collapse. Moreover, after drying, these SAMs can be easily removed using a gentle air-plasma treatment right before the next fabrication step, leaving a clean nanopillar surface behind. Therefore, our approach provides a facile and effective method to prevent the drying-induced pattern collapse in micro- and nanofabrication processes.
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Affiliation(s)
- Tanmay Ghosh
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
| | - Eva-Corinna Fritz
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Deepan Balakrishnan
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
| | - Ziyu Zhang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Nandi Vrancken
- imec, Kapeldreef 75, Leuven B-3001, Belgium
- Department of Materials & Chemistry, Vrije Universiteit Brussel, Brussel B-1050, Belgium
| | - Utkarsh Anand
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
| | - Hong Zhang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - N Duane Loh
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
| | - XiuMei Xu
- imec, Kapeldreef 75, Leuven B-3001, Belgium
| | | | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
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3
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Wang W, Yan H, Anand U, Mirsaidov U. Visualizing the Conversion of Metal–Organic Framework Nanoparticles into Hollow Layered Double Hydroxide Nanocages. J Am Chem Soc 2021; 143:1854-1862. [DOI: 10.1021/jacs.0c10285] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wenhui Wang
- Department of Physics, National University of Singapore, 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, 117557, Singapore
| | - Hongwei Yan
- Department of Physics, National University of Singapore, 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, 117557, Singapore
| | - Utkarsh Anand
- Department of Physics, National University of Singapore, 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, 117557, Singapore
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore, 117551, Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, 117557, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 117546, Singapore
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
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4
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Abstract
Background Uremic neuropathy commonly affects patients with chronic kidney disease, with
painful sensations in the feet, followed by numbness and weakness in the
legs and hands. The symptoms usually resolve following kidney
transplantation, but the mechanisms of uremic neuropathy and associated pain
symptoms remain unknown. As blood urea levels are elevated in patients with
chronic kidney disease, we examined the morphological and functional effects
of clinically observed levels of urea on sensory neurons. Methods Rat dorsal root ganglion neurons were treated with 10 or 50 mmol/L urea for
48 h, fixed and immunostained for PGP9.5 and βIII tubulin
immunofluorescence. Neurons were also immunostained for TRPV1, TRPM8 and
Gap43 expression, and the capsaicin sensitivity of urea- or vehicle-treated
neurons was determined. Results Urea-treated neurons had degenerating neurites with diminished PGP9.5
immunofluorescence, and swollen, retracted growth cones. βIII tubulin
appeared clumped after urea treatment. After 48 hours urea treatment,
neurite lengths were significantly reduced to 60 ± 2.6% (10 mmol/L,
**P < 0.01), and to 56.2 ± 3.3% (50 mmol/L, **P < 0.01), compared with
control neurons. Fewer neurons survived urea treatment, with 70.08 ± 13.3%
remaining after 10 mmol/L (*P < 0.05) and 61.49 ± 7.4% after 50 mmol/L
urea treatment (**P < 0.01), compared with controls. The proportion of
neurons expressing TRPV1 was reduced after urea treatment, but not TRPM8
expressing neurons. In functional studies, treatment with urea resulted in
dose-dependent neuronal sensitization. Capsaicin responses were
significantly increased to 115.29 ± 3.4% (10 mmol/L, **P < 0.01) and
125.3 ± 4.2% (50 mmol/L, **P < 0.01), compared with controls.
Sensitization due to urea was eliminated in the presence of the TRPV1
inhibitor SB705498, the mitogen-activated protein kinase kinase inhibitor
PD98059, the PI3 kinase inhibitor LY294002 and the TRPM8 inhibitor
N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide
(AMTB hydrochloride). Conclusion Neurite degeneration and sensitization are consistent with uremic neuropathy
and provide a disease-relevant model to test new treatments.
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Affiliation(s)
- U Anand
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK.,Nanomedicine Research Laboratory, Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - Y Korchev
- Nanomedicine Research Laboratory, Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - P Anand
- Peripheral Neuropathy Unit, Centre for Clinical Translation, Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
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5
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Vrancken N, Ghosh T, Anand U, Aabdin Z, Chee SW, Baraissov Z, Terryn H, Gendt SD, Tao Z, Xu X, Holsteyns F, Mirsaidov U. Nanoscale Elastocapillary Effect Induced by Thin-Liquid-Film Instability. J Phys Chem Lett 2020; 11:2751-2758. [PMID: 32187494 DOI: 10.1021/acs.jpclett.0c00218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dense arrays of high-aspect-ratio (HAR) vertical nanostructures are essential elements of microelectronic components, photovoltaics, nanoelectromechanical, and energy storage devices. One of the critical challenges in manufacturing the HAR nanostructures is to prevent their capillary-induced aggregation during solution-based nanofabrication processes. Despite the importance of controlling capillary effects, the detailed mechanisms of how a solution interacts with nanostructures are not well understood. Using in situ liquid cell transmission electron microscopy (TEM), we track the dynamics of nanoscale drying process of HAR silicon (Si) nanopillars in real-time and identify a new mechanism responsible for pattern collapse and nanostructure aggregation. During drying, deflection and aggregation of nanopillars are driven by thin-liquid-film instability, which results in much stronger capillary interactions between the nanopillars than the commonly proposed lateral meniscus interaction forces. The importance of thin-film instability in dewetting has been overlooked in prevalent theories on elastocapillary aggregation. The new dynamic mechanism revealed by in situ visualization is essential for the development of robust nanofabrication processes.
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Affiliation(s)
- Nandi Vrancken
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Materials & Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium
- IMEC, Kapeldreef 75, Leuven B-3001, Belgium
| | - Tanmay Ghosh
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
| | - Utkarsh Anand
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Zainul Aabdin
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 138634, Singapore
| | - See Wee Chee
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Zhaslan Baraissov
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Herman Terryn
- Department of Materials & Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium
| | - Stefan De Gendt
- IMEC, Kapeldreef 75, Leuven B-3001, Belgium
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Zheng Tao
- IMEC, Kapeldreef 75, Leuven B-3001, Belgium
| | - XiuMei Xu
- IMEC, Kapeldreef 75, Leuven B-3001, Belgium
| | | | - Utkur Mirsaidov
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore
- Department of Physics, National University of Singapore, Singapore 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Materials Science, National University of Singapore, Singapore 117575, Singapore
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6
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Ankale N, Nagmoti JM, Anand U. Mycological Profile in Otomycosis Patients: A Cross Sectional Hospital Based Study in Tertiary Care Centre. BJOHNS 2019. [DOI: 10.47210/bjohns.2019.v27i3.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Introduction
This study was conducted to study the fungal profile in otomycosis patients in the tropical region of North Karnataka. A total of 108 samples of symptomatic otomycosis were investigated in this study.
Materials and Methods
Aural swabs were collected on 1st visit and these swabs were immediately inoculated over Sabouraud’s dextrose agar media and incubated at 37 degree Celsius for culture of fungi.
Results
Fungal pathogens were isolated in 89 samples, 18 samples were negative and 1 sample was reported as being contaminated. Fungi belonging to genus Aspergillus was isolated in 92.11% of cases of which Aspergillus niger was commonest isolated in 38(41.57%) followed br Aspergillus flavus 32(35.95%) and Aspergillus fumigatus 7(7.86%). Candida species were found in 2(2.24%) and Mucor in 1(1.12%). The most common symptom was Itching 91(84.25%). In this study ear discharge was the commonest finding (44.44%) followed by Black mycotic plug (28.70%).
Conclusion
Otomycosis is a condition encountered in hot, humid climate with symptoms like itching and ear discharge. Aspergillus and Candida are the fungal species responsible for majority of cases. Local antifungal treatment with measures like keeping the ear dry resolves most of the cases.
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7
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Chee SW, Anand U, Bisht G, Tan SF, Mirsaidov U. Direct Observations of the Rotation and Translation of Anisotropic Nanoparticles Adsorbed at a Liquid-Solid Interface. Nano Lett 2019; 19:2871-2878. [PMID: 30932500 DOI: 10.1021/acs.nanolett.8b04962] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We can learn about the interactions between nanoparticles (NPs) in solution and solid surfaces by tracking how they move. Here, we use liquid cell transmission electron microscopy (TEM) to follow directly the translation and rotation of Au nanobipyramids (NBPs) and nanorods (NRs) adsorbed onto a SiN x surface at a rate of 300 frames per second. This study is motivated by the enduring need for a detailed description of NP motion on this common surface in liquid cell TEM. We will show that NPs move intermittently on the time scales of milliseconds. First, they rotate in two ways: (1) rotation around the center of mass and (2) pivoted rotation at the tips. These rotations also lead to different modes of translation. A NP can move through small displacements in the direction roughly parallel to its body axis (shuffling) or with larger steps via multiple tip-pivoted rotations. Analysis of the trajectories indicates that both displacements and rotation angles follow heavy-tailed power law distributions, implying anomalous diffusion. The spatial and temporal resolution afforded by our approach also revealed differences between the different NPs. The 50 nm NRs and 100 nm NBPs moved with a combination of shuffles and rotation-mediated displacements after illumination by the electron beam. With increasing electron fluence, 50 nm NRs also started to move via desorption-mediated jumps. The 70 nm NRs did not exhibit translational motion and only made small rotations. These results describe how NP dynamics evolve under the electron beam and how intermittent pinning and release at specific adsorption sites on the solid surface control NP motion at the liquid-solid interface. We also discuss the effect of SiN x surface treatment on NP motion, demonstrating how our approach can provide broader insights into interfacial transport.
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Affiliation(s)
- See Wee Chee
- Department of Physics , National University of Singapore , Singapore 117551
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
| | - Utkarsh Anand
- Department of Physics , National University of Singapore , Singapore 117551
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
| | - Geeta Bisht
- Department of Physics , National University of Singapore , Singapore 117551
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Shu Fen Tan
- Department of Physics , National University of Singapore , Singapore 117551
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Utkur Mirsaidov
- Department of Physics , National University of Singapore , Singapore 117551
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- NUSNNI-NanoCore, Faculty of Engineering , National University of Singapore , Singapore 117581
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575
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8
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Tian X, Anand U, Mirsaidov U, Zheng H. Spontaneous Reshaping and Splitting of AgCl Nanocrystals under Electron Beam Illumination. Small 2018; 14:e1803231. [PMID: 30369027 DOI: 10.1002/smll.201803231] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/09/2018] [Indexed: 06/08/2023]
Abstract
AgCl is photosensitive and thus often used as micromotors. However, the dynamics of individual AgCl nanoparticle motion in liquids upon illumination remains elusive. Here, using liquid cell transmission electron microscope (TEM), AgCl nanocrystals reshaping and splitting spontaneously in an aqueous solution under electron beam illumination are observed. It is found that the AgCl nanocrystals are negatively charged in the liquid environment, where the charge induces a repulsive Coulomb force that reshapes and stretches those nanocrystals. Upon extensive stretching, the AgCl nanocrystal splits into small nanocrystals and each nanocrystal retracts back into cuboid shapes due to the cohesive surface. This analysis shows that each nanocrystal maintains a single crystal rocksalt structure during splitting. The splitting of AgCl nanocrystals is analogous to the electrified liquid droplets or other reported the Coulomb fission phenomenon, but with distinctive structural properties. Revealing of the dynamic behavior of AgCl nanocrystals opens the opportunity to explore their potential applications as actuators for nanodevices.
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Affiliation(s)
- Xuezeng Tian
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Berkeley Education Alliance for Research in Singapore, Singapore, 138602, Singapore
| | - Utkarsh Anand
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, 117557, Singapore
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
| | - Utkur Mirsaidov
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, 117557, Singapore
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Berkeley Education Alliance for Research in Singapore, Singapore, 138602, Singapore
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Tan SF, Bisht G, Anand U, Bosman M, Yong XE, Mirsaidov U. In Situ Kinetic and Thermodynamic Growth Control of Au-Pd Core-Shell Nanoparticles. J Am Chem Soc 2018; 140:11680-11685. [PMID: 30099870 DOI: 10.1021/jacs.8b05217] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
One-pot wet-chemical synthesis is a simple way to obtain nanoparticles (NPs) with a well-defined shape and composition. However, achieving good control over NP synthesis would require a comprehensive understanding of the mechanisms of NP formation, something that is challenging to obtain experimentally. Here, we study the formation of gold (Au) core-palladium (Pd) shell NPs under kinetically and thermodynamically controlled reaction conditions using in situ liquid cell transmission electron microscopy (TEM). By controlling the reaction temperature, we demonstrate that it is possible to tune the shape of Au nanorods to Au-Pd arrow-headed structures or to cuboidal core-shell NPs. Our in situ studies show that the reaction temperature can switch the Pd shell growth between the kinetically and thermodynamically dominant regimes. The mechanistic insights reported here reveal how the reaction temperature affects the packing of the capping agents and how the facet selection of depositing shell atoms drives the shell formation under different kinetic conditions, which is useful for synthesizing NPs with greater design flexibility in shape and elemental composition for various technological applications.
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Affiliation(s)
- Shu Fen Tan
- Department of Physics , National University of Singapore , Singapore 117551.,Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Geeta Bisht
- Department of Physics , National University of Singapore , Singapore 117551.,Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Utkarsh Anand
- Department of Physics , National University of Singapore , Singapore 117551.,Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Michel Bosman
- Department of Materials Science and Engineering , National University of Singapore , Singapore 117575.,Institute of Materials Research and Engineering , Agency for Science, Technology, and Research (A*STAR) , Singapore 138634
| | - Xin Ee Yong
- Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557
| | - Utkur Mirsaidov
- Department of Physics , National University of Singapore , Singapore 117551.,Centre for BioImaging Sciences, Department of Biological Sciences , National University of Singapore , Singapore 117557.,Department of Materials Science and Engineering , National University of Singapore , Singapore 117575.,Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546.,NUSNNI-NanoCore , National University of Singapore , Singapore 117411
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10
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Annamalai S, Esposito M, Reyelt L, Natov P, Jorde L, Chouinard P, Liu Q, Anand U, Heuring J, Clifton W, Kapur N. Hemodynamic Effects of an Intra-aortic Micro-axial Flow Pump in a Swine Model of Ischemic Heart Failure. J Heart Lung Transplant 2018. [DOI: 10.1016/j.healun.2018.01.656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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11
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Aabdin Z, Xu XM, Sen S, Anand U, Král P, Holsteyns F, Mirsaidov U. Transient Clustering of Reaction Intermediates during Wet Etching of Silicon Nanostructures. Nano Lett 2017; 17:2953-2958. [PMID: 28418255 DOI: 10.1021/acs.nanolett.7b00196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Wet chemical etching is a key process in fabricating silicon (Si) nanostructures. Currently, wet etching of Si is proposed to occur through the reaction of surface Si atoms with etchant molecules, forming etch intermediates that dissolve directly into the bulk etchant solution. Here, using in situ transmission electron microscopy (TEM), we follow the nanoscale wet etch dynamics of amorphous Si (a-Si) nanopillars in real-time and show that intermediates generated during alkaline wet etching first aggregate as nanoclusters on the Si surface and then detach from the surface before dissolving in the etchant solution. Molecular dynamics simulations reveal that the molecules of etch intermediates remain weakly bound to the hydroxylated Si surface during the etching and aggregate into nanoclusters via surface diffusion instead of directly diffusing into the etchant solution. We confirmed this model experimentally by suppressing the formation of nanoclusters of etch intermediates on the Si surfaces by shielding the hydroxylated Si sites with large ions. These results suggest that the interaction of etch intermediates with etching surfaces controls the solubility of reaction intermediates and is an important parameter in fabricating densely packed clean 3D nanostructures for future generation microelectronics.
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Affiliation(s)
- Zainul Aabdin
- Department of Physics, National University of Singapore , 117551, Singapore
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore , 117557, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546, Singapore
- NUSNNI-NanoCore, National University of Singapore , 117411, Singapore
| | - Xiu Mei Xu
- imec , Kapeldreef 75, Leuven, B-3001, Belgium
| | | | - Utkarsh Anand
- Department of Physics, National University of Singapore , 117551, Singapore
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore , 117557, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546, Singapore
- NUSNNI-NanoCore, National University of Singapore , 117411, Singapore
| | - Petr Král
- Department of Biopharmaceutical Sciences, University of Illinois at Chicago , Chicago, Illinois 60612, United States
| | | | - Utkur Mirsaidov
- Department of Physics, National University of Singapore , 117551, Singapore
- Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore , 117557, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546, Singapore
- NUSNNI-NanoCore, National University of Singapore , 117411, Singapore
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12
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Abstract
Nanoparticle (NP) self-assembly has been recognized as an important technological process for forming ordered nanostructures. However, the detailed dynamics of the assembly processes remain poorly understood. Using in situ liquid cell transmission electron microscopy, we describe the assembly modes of gold (Au) nanorods (NRs) in solution mediated by hydrogen bonding between NR-bound cysteamine linker molecules. Our observations reveal that by tuning the linker concentration, two different NR assembly modes can be achieved. These assembly modes proceed via the (1) end-to-end and (2) side-to-side attachment of NRs at low and high linker concentrations in solution, respectively. In addition, our time-resolved observations reveal that the side-to-side NR assemblies can occur through two different pathways: (i) prealigned attachment, where two Au NRs prealign to be parallel prior to assembly, and (ii) postattachment alignment, where two Au NRs first undergo end-to-end attachment and pivot around the attachment point to form the side-to-side assembly. We attributed the observed assembly modes to the distribution of linkers on the NR surfaces and the electrostatic interactions between the NRs. The intermediate steps in the assembly reported here reveal how the shape and surface functionalities of NPs drive their self-assembly, which is important for the rational design of hierarchical nanostructures.
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Affiliation(s)
- Shu Fen Tan
- Department of Physics, National University of Singapore , 117551 Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 117557 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546 Singapore
| | - Utkarsh Anand
- Department of Physics, National University of Singapore , 117551 Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 117557 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546 Singapore
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore , 117551 Singapore
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 117557 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 117546 Singapore
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
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13
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Anand U, Sinisi M, Fox M, MacQuillan A, Quick T, Korchev Y, Bountra C, McCarthy T, Anand P. Mycolactone-mediated neurite degeneration and functional effects in cultured human and rat DRG neurons: Mechanisms underlying hypoalgesia in Buruli ulcer. Mol Pain 2016; 12:12/0/1744806916654144. [PMID: 27325560 PMCID: PMC4956182 DOI: 10.1177/1744806916654144] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/16/2016] [Indexed: 01/08/2023] Open
Abstract
Background Mycolactone is a polyketide toxin secreted by the mycobacterium Mycobacterium ulcerans, responsible for the extensive hypoalgesic skin lesions characteristic of patients with Buruli ulcer. A recent pre-clinical study proposed that mycolactone may produce analgesia via activation of the angiotensin II type 2 receptor (AT2R). In contrast, AT2R antagonist EMA401 has shown analgesic efficacy in animal models and clinical trials for neuropathic pain. We therefore investigated the morphological and functional effects of mycolactone in cultured human and rat dorsal root ganglia (DRG) neurons and the role of AT2R using EMA401. Primary sensory neurons were prepared from avulsed cervical human DRG and rat DRG; 24 h after plating, neurons were incubated for 24 to 96 h with synthetic mycolactone A/B, followed by immunostaining with antibodies to PGP9.5, Gap43, β tubulin, or Mitotracker dye staining. Acute functional effects were examined by measuring capsaicin responses with calcium imaging in DRG neuronal cultures treated with mycolactone. Results Morphological effects: Mycolactone-treated cultures showed dramatically reduced numbers of surviving neurons and non-neuronal cells, reduced Gap43 and β tubulin expression, degenerating neurites and reduced cell body diameter, compared with controls. Dose-related reduction of neurite length was observed in mycolactone-treated cultures. Mitochondria were distributed throughout the length of neurites and soma of control neurons, but clustered in the neurites and soma of mycolactone-treated neurons. Functional effects: Mycolactone-treated human and rat DRG neurons showed dose-related inhibition of capsaicin responses, which were reversed by calcineurin inhibitor cyclosporine and phosphodiesterase inhibitor 3-isobutyl-1-Methylxanthine, indicating involvement of cAMP/ATP reduction. The morphological and functional effects of mycolactone were not altered by Angiotensin II or AT2R antagonist EMA401. Conclusion Mycolactone induces toxic effects in DRG neurons, leading to impaired nociceptor function, neurite degeneration, and cell death, resembling the cutaneous hypoalgesia and nerve damage in individuals with M. Ulcerans infection.
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Affiliation(s)
- U Anand
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - M Sinisi
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - M Fox
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - A MacQuillan
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - T Quick
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - Y Korchev
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - C Bountra
- University of Oxford Structural Genomics Consortium, Headington, Oxford, UK
| | - T McCarthy
- Spinifex Pharmaceuticals Pty Ltd, St. Preston, VIC, Australia
| | - P Anand
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
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14
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Abstract
Dendrite formation on the electrodes of a rechargeable battery during the charge-discharge cycle limits its capacity and application due to short-circuits and potential ignition. However, understanding of the underlying dendrite growth and dissolution mechanisms is limited. Here, the electrochemical growth and dissolution of silver dendrites on platinum electrodes immersed in an aqueous silver nitrate (AgNO3) electrolyte solution was investigated using in situ liquid-cell transmission electron microscopy (TEM). The dissolution of Ag dendrites in an AgNO3 solution with added cetyltrimethylammonium bromide (CTAB) surfactant was compared to the dissolution of Ag dendrites in a pure aqueous AgNO3 solution. Significantly, when CTAB was added, dendrite dissolution proceeded in a step-by-step manner, resulting in nanoparticle formation and transient microgrowth stages due to Ostwald ripening. This resulted in complete dissolution of dendrites and "cleaning" of the cell of any silver metal. This is critical for practical battery applications because "dead" lithium is known to cause short circuits and high-discharge rates. In contrast to this, in a pure aqueous AgNO3 solution, without surfactant, dendrites dissolved incompletely back into solution, leaving behind minute traces of disconnected silver particles. Finally, a mechanism for the CTAB-influenced dissolution of silver dendrites was proposed based on electrical field dependent binding energy of CTA(+) to silver.
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Affiliation(s)
- Colm O'Regan
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546
| | - Xi Zhu
- Division of Materials Science, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798
| | - Jun Zhong
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
| | - Utkarsh Anand
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Jingyu Lu
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Haibin Su
- Division of Materials Science, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798
| | - Utkur Mirsaidov
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117543
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
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15
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Lin G, Zhu X, Anand U, Liu Q, Lu J, Aabdin Z, Su H, Mirsaidov U. Nanodroplet-Mediated Assembly of Platinum Nanoparticle Rings in Solution. Nano Lett 2016; 16:1092-1096. [PMID: 26726725 DOI: 10.1021/acs.nanolett.5b04323] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Soft fluidlike nanoscale objects can drive nanoparticle assembly by serving as a scaffold for nanoparticle organization. The intermediate steps in these template-directed nanoscale assemblies are important but remain unresolved. We used real-time in situ transmission electron microscopy to follow the assembly dynamics of platinum nanoparticles into flexible ringlike chains around ethylenediaminetetraacetic acid nanodroplets dispersed in solution. In solution, these nanoring assemblies form via sequential attachment of the nanoparticles to binding sites located along the circumference of the nanodroplets, followed by the rearrangement and reorientation of the attached nanoparticles. Additionally, larger nanoparticle ring assemblies form via the coalescence of smaller ring assemblies. The intermediate steps of assembly reported here reveal how fluidlike nanotemplates drive nanoparticle organization, which can aid the future design of new nanomaterials.
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Affiliation(s)
- Guanhua Lin
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Xi Zhu
- School of Materials Sciences and Engineering, Nanyang Technological University , Singapore 639798
| | - Utkarsh Anand
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Qi Liu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Jingyu Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Zainul Aabdin
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Haibin Su
- School of Materials Sciences and Engineering, Nanyang Technological University , Singapore 639798
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore , 117543
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
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16
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Abstract
When any two surfaces in a solution come within a distance the size of a few solvent molecules, they experience a solvation force or a hydration force when the solvent is water. Although the range and magnitude of hydration forces are easy to characterize, the effects of these forces on the transient steps of interaction dynamics between nanoscale bodies in solution are poorly understood. Here, using in situ transmission electron microscopy, we show that when two gold nanoparticles in water approach each other at a distance within two water molecules (∼5 Å), which is the combined thickness of the hydration shell of each nanoparticle, they form a sterically stabilized transient nanoparticle dimer. The interacting surfaces of the nanoparticles come in contact and undergo coalescence only after these surfaces are fully dehydrated. Our observations of transient steps in nanoparticle interactions, which reveal the formation of hydration layer mediated metastable nanoparticle pairs in solution, have significant implications for many natural and industrial processes.
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Affiliation(s)
- Utkarsh Anand
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore, 117551
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore, 117543
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Jingyu Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore, 117551
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore, 117543
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Duane Loh
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore, 117551
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore, 117543
| | - Zainul Aabdin
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore, 117551
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore, 117543
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore, 117551
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , 14 Science Drive 4, Singapore, 117543
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- NanoCore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
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17
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Abstract
Nanoscale defects on a substrate affect the sliding motion of water droplets. Using in situ transmission electron microscopy imaging, we visualized the depinning dynamics of water nanodroplets from gold nanoparticles on a flat SiNx surface. Our observations showed that nanoscale pinning effects of the gold nanoparticle oppose the lateral forces, resulting in stretching, even breakup, of the water nanodroplet. Using continuum long wave theory, we modeled the dynamics of a nanodroplet depinning from a nanoparticle of comparable length scales, and the model results are consistent with experimental findings and show formation of a capillary bridge prior to nanodroplet depinning. Our findings have important implications on surface cleaning at the nanoscale.
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Affiliation(s)
- Qi Liu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , Science Drive 4, Singapore 117543
- Nanocore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Fong Yew Leong
- A*STAR Institute of High Performance Computing , 1 Fusionopolis Way, Connexis, Singapore 138632
| | - Zainul Aabdin
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , Science Drive 4, Singapore 117543
- Nanocore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Utkarsh Anand
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , Science Drive 4, Singapore 117543
- Nanocore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
| | - Tran Si Bui Quang
- A*STAR Institute of High Performance Computing , 1 Fusionopolis Way, Connexis, Singapore 138632
| | - Utkur Mirsaidov
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Centre for BioImaging Sciences, Department of Biological Sciences, National University of Singapore , Science Drive 4, Singapore 117543
- Nanocore, National University of Singapore , 4 Engineering Drive 3, Singapore 117576
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18
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Abstract
Nanocrystal bonding is an important phenomenon in crystal growth and nanoscale welding. Here, we show that for gold nanocrystals bonding in solution can follow two distinct pathways: (1) coherent, defect-free bonding occurs when two nanocrystals attach with their lattices aligned to within a critical angle; and (2) beyond this critical angle, defects form at the interfaces where the nanocrystals merge. The critical misalignment angle for ∼10 nm crystals is ∼15° in both in situ experiments and full-atom molecular dynamics simulations. Understanding the origin of this critical angle during bonding may help us predict and manage strain profiles in nanoscale assemblies and inspire techniques toward reproducible and extensible architectures using only basic crystalline blocks.
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Affiliation(s)
- Zainul Aabdin
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore , 117551
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19
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Anand U, Facer P, Yiangou Y, Sinisi M, Fox M, McCarthy T, Bountra C, Korchev YE, Anand P. Angiotensin II type 2 receptor (AT2 R) localization and antagonist-mediated inhibition of capsaicin responses and neurite outgrowth in human and rat sensory neurons. Eur J Pain 2013; 17:1012-26. [PMID: 23255326 PMCID: PMC3748799 DOI: 10.1002/j.1532-2149.2012.00269.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2012] [Indexed: 01/05/2023]
Abstract
BACKGROUND The angiotensin II (AngII) receptor subtype 2 (AT2 R) is expressed in sensory neurons and may play a role in nociception and neuronal regeneration. METHODS We used immunostaining with characterized antibodies to study the localization of AT2 R in cultured human and rat dorsal root ganglion (DRG) neurons and a range of human tissues. The effects of AngII and AT2 R antagonist EMA401 on capsaicin responses in cultured human and rat (DRG) neurons were measured with calcium imaging, on neurite length and density with Gap43 immunostaining, and on cyclic adenosine monophosphate (cAMP) expression using immunofluorescence. RESULTS AT2 R expression was localized in small-/medium-sized cultured neurons of human and rat DRG. Treatment with the AT2 R antagonist EMA401 resulted in dose-related functional inhibition of capsaicin responses (IC50 = 10 nmol/L), which was reversed by 8-bromo-cAMP, and reduced neurite length and density; AngII treatment significantly enhanced capsaicin responses, cAMP levels and neurite outgrowth. The AT1 R antagonist losartan had no effect on capsaicin responses. AT2 R was localized in sensory neurons of human DRG, and nerve fibres in peripheral nerves, skin, urinary bladder and bowel. A majority sub-population (60%) of small-/medium-diameter neuronal cells were immunopositive in both control post-mortem and avulsion-injured human DRG; some very small neurons appeared to be intensely immunoreactive, with TRPV1 co-localization. While AT2 R levels were reduced in human limb peripheral nerve segments proximal to injury, they were preserved in painful neuromas. CONCLUSIONS AT2 R antagonists could be particularly useful in the treatment of chronic pain and hypersensitivity associated with abnormal nerve sprouting.
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Affiliation(s)
- U Anand
- Peripheral Neuropathy Unit, Department of Clinical Neuroscience, Imperial College London, UK
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20
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21
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Krishnamurthy N, Arumugasamy K, Anand U, Anand CV, Aruna V, Venu G, Gayathri R. Effect of hemodialysis on circulating cystatin c levels in patients with end stage renal disease. Indian J Clin Biochem 2010; 25:43-6. [PMID: 23105882 DOI: 10.1007/s12291-010-0009-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Plasma cystatin C is an emerging parameter to assess kidney function. Its utility in assessing the adequacy of hemodialysis in patients with end-stage-renal disease has however not been established with certainty. This study was therefore carried out to assess the usefulness of serum cystatin C estimation in patients undergoing low flux membrane hemodialysis. Serum creatinine and cystatin C were estimated in 20 patients before and after undergoing hemodialysis. The mean serum creatinine decreased from a pre-dialysis value of 7.72 mg/dL to a post-dialysis value of 2.90 mg/dL. On the contrary, the mean serum cystatin C levels were found to increase from a pre-dialysis value of 5.97 mg/L to a post-dialysis value of 8.25 mg/L. Therefore, serum cystatin C cannot be used to monitor dialysis adequacy. It however, serves as a surrogate marker of the inadequacy of low flux membrane bicarbonate hemodialysis in clearing low molecular weight proteins from the circulation.
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Affiliation(s)
- N Krishnamurthy
- Department of Biotechnology, Sathyabama University, Chennai, India
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22
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Anand U, Otto WR, Facer P, Zebda N, Selmer I, Gunthorpe MJ, Chessell IP, Sinisi M, Birch R, Anand P. TRPA1 receptor localisation in the human peripheral nervous system and functional studies in cultured human and rat sensory neurons. Neurosci Lett 2008; 438:221-7. [PMID: 18456404 DOI: 10.1016/j.neulet.2008.04.007] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 04/02/2008] [Accepted: 04/02/2008] [Indexed: 11/17/2022]
Abstract
TRPA1 is a receptor expressed by sensory neurons, that is activated by low temperature (<17 degrees C) and plant derivatives such as cinnamaldehyde and isoeugenol, to elicit sensations including pain. Using immunohistochemistry, we have, for the first time, localised TRPA1 in human DRG neurons, spinal cord motoneurones and nerve roots, peripheral nerves, intestinal myenteric plexus neurones, and skin basal keratinocytes. TRPA1 co-localised with a subset of hDRG neurons positive for TRPV1, the heat and capsaicin receptor. The number of small/medium TRPA1 positive neurons (< or =50 microm) was increased after hDRG avulsion injury [percentage of cells, median (range): controls 16.5 (7-23); injured 46 (34-55); P<0.005], but the number of large TRPA1 neurons was unchanged [control 19.5 (13-31); injured 21 (11-35)]. Similar TRPA1 changes were observed in cultured hDRG neurons, after exposure to a combination of key neurotrophic factors NGF, GDNF and NT-3 (NTFs) in vitro. We used calcium imaging to examine responses of HEK cells transfected with hTRPA1 cDNA, and of human and rat DRG neurons cultured with or without added NTFs, to cinnamaldehyde (CA) and isoeugenol (IE). Exposure to NTFs in vitro sensitized cultured human sensory neuronal responses to CA; repeated CA exposure produced desensitisation. In rDRG neurons, low (225 microM) CA preincubation enhanced capsaicin responses, while high (450 microM and 2mM) CA caused inhibition which was partially reversed in the presence of 8 bromo cAMP, indicating receptor dephosphorylation. While TRPA1 localisation is more widespread than TRPV1, it represents a promising novel drug target for the treatment of chronic pain and hypersensitivity.
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Affiliation(s)
- U Anand
- Peripheral Neuropathy Unit, Imperial College London, Area A, Ground Floor, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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23
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De Beule PAA, Dunsby C, Galletly NP, Stamp GW, Chu AC, Anand U, Anand P, Benham CD, Naylor A, French PMW. A hyperspectral fluorescence lifetime probe for skin cancer diagnosis. Rev Sci Instrum 2007; 78:123101. [PMID: 18163714 DOI: 10.1063/1.2818785] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The autofluorescence of biological tissue can be exploited for the detection and diagnosis of disease but, to date, its complex nature and relatively weak signal levels have impeded its widespread application in biology and medicine. We present here a portable instrument designed for the in situ simultaneous measurement of autofluorescence emission spectra and temporal decay profiles, permitting the analysis of complex fluorescence signals. This hyperspectral fluorescence lifetime probe utilizes two ultrafast lasers operating at 355 and 440 nm that can excite autofluorescence from many different biomolecules present in skin tissue including keratin, collagen, nicotinamide adenine dinucleotide (phosphate), and flavins. The instrument incorporates an optical fiber probe to provide sample illumination and fluorescence collection over a millimeter-sized area. We present a description of the system, including spectral and temporal characterizations, and report the preliminary application of this instrument to a study of recently resected (<2 h) ex vivo skin lesions, illustrating its potential for skin cancer detection and diagnosis.
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Affiliation(s)
- P A A De Beule
- Department of Physics, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
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24
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Kumar S, Dunsby C, De Beule PAA, Owen DM, Anand U, Lanigan PMP, Benninger RKP, Davis DM, Neil MAA, Anand P, Benham C, Naylor A, French PMW. Multifocal multiphoton excitation and time correlated single photon counting detection for 3-D fluorescence lifetime imaging. Opt Express 2007; 15:12548-61. [PMID: 19550524 DOI: 10.1364/oe.15.012548] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We report a multifocal multiphoton time-correlated single photon counting (TCSPC) fluorescence lifetime imaging (FLIM) microscope system that uses a 16 channel multi-anode PMT detector. Multiphoton excitation minimizes out-of-focus photobleaching, multifocal excitation reduces non-linear in-plane photobleaching effects and TCSPC electronics provide photon-efficient detection of the fluorescence decay profile. TCSPC detection is less prone to bleaching- and movement-induced artefacts compared to wide-field time-gated or frequency-domain FLIM. This microscope is therefore capable of acquiring 3-D FLIM images at significantly increased speeds compared to single beam multiphoton microscopy and we demonstrate this with live cells expressing a GFP tagged protein. We also apply this system to time-lapse FLIM of NAD(P)H autofluorescence in single live cells and report measurements on the change in the fluorescence decay profile following the application of a known metabolic inhibitor.
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25
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Anand U, Otto WR, Casula MA, Day NC, Davis JB, Bountra C, Birch R, Anand P. The effect of neurotrophic factors on morphology, TRPV1 expression and capsaicin responses of cultured human DRG sensory neurons. Neurosci Lett 2006; 399:51-6. [PMID: 16481104 DOI: 10.1016/j.neulet.2006.01.046] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/15/2006] [Accepted: 01/20/2006] [Indexed: 11/23/2022]
Abstract
We have studied the effect of key neurotrophic factors (NTFs) on morphology, levels of the vanilloid receptor-1 (TRPV1) and responses to capsaicin in adult human sensory neurons in vitro. Avulsed dorsal root ganglia (DRG, n = 5) were cultured with or without a combination of nerve growth factor (NGF), glial cell (line)-derived growth factor (GDNF) and neurotrophin3 (NT3) for 5 days. In the absence of NTFs, the diameter of neurons ranged from 20 to 100 microm (mean 42 +/- 4 microm). Adding NTFs caused a significant increase in neuronal sizes, up to 120 microm (mean diameter 62 +/- 5 microm, P < 0.01, t-test), an overall 35% increase of TRPV1-positive neurons (P < 0.003), and notably of large TRPV1-positive neurons > 80 microm (P < 0.05). Responses to capsaicin were significantly enhanced with calcium ratiometry (P < 0.0001). Short duration (1h) exposure of dissociated sensory neurons to NTFs increased numbers of TRPV1-positive neurons, but not of TRPV3, Nav 1.8 and IK1 and the morphological size-distribution remained similar to intact post-mortem DRG neurons. NTFs thus increase size, elevate TRPV1 levels and enhance capsaicin responses in cultured human DRG neurons; these changes may relate to pathophysiology in disease states, and provide an in vitro model to study novel analgesics.
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Affiliation(s)
- U Anand
- Peripheral Neuropathy Unit, Imperial College, Area A, Ground Floor, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
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Taherzadeh O, Otto WR, Anand U, Nanchahal J, Anand P. Influence of human skin injury on regeneration of sensory neurons. Cell Tissue Res 2003; 312:275-80. [PMID: 12733058 DOI: 10.1007/s00441-003-0724-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2002] [Accepted: 03/24/2003] [Indexed: 12/18/2022]
Abstract
The regeneration of sensory nerve fibres is regulated by trophic factors released from their target tissue, particularly the basal epidermis, and matrix molecules. Means to modulate this response may be useful for the treatment of neuromas and painful hypertrophic scars and of sensory deficits in skin grafts and flaps. We have developed an in vitro model of sensory neuron regeneration on human skin in order to study the mechanisms of sensory dysfunction in pathological conditions. Adult rat sensory neurons were co-cultured with unfixed cryosections of normal or injured (crushed) human skin for 72 h. Neurons were immunostained for growth-associated protein-43 and the neurite lengths of neuronal cell bodies situated in various skin regions were measured. Two-way analysis of variance was performed. Neurites of sensory cell bodies on epidermis of normal skin were the shortest, with a mean +/- SEM of 75+/-10 micrometer, whereas those of cells on the dermo-epidermal junction were the longest, with a mean +/- SEM of 231+/-18 micrometer. Neurons on the dermo-epidermal junction of injured skin had significantly longer neurites than those on the same region of normal skin (mean +/- SEM = 289+/-21 micrometer). Regeneration of sensory neurons may be influenced by extracellular matrix molecules, matrix-binding growth factors and trophic factors. Altered substrate or trophic factors in injured skin may explain the increase of neurite lengths. This in vitro model may be useful for studying the molecular mechanisms of sensory recovery and the development of neuropathic pain following peripheral nerve injury.
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Affiliation(s)
- O Taherzadeh
- Peripheral Neuropathy Unit, Division of Neuroscience and Psychological Medicine, Imperial College of Science, Technology and Medicine, Hammersmith Hospital, Du Cane Road, W12 0NN, London, UK
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Boettger MK, Till S, Chen MX, Anand U, Otto WR, Plumpton C, Trezise DJ, Tate SN, Bountra C, Coward K, Birch R, Anand P. Calcium-activated potassium channel SK1- and IK1-like immunoreactivity in injured human sensory neurones and its regulation by neurotrophic factors. Brain 2002; 125:252-63. [PMID: 11844726 DOI: 10.1093/brain/awf026] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium ion channels SK and IK (small and intermediate conductance, respectively) may be important in the pathophysiology of pain following nerve injury, as SK channels are known to impose a period of reduced excitability after each action potential by afterhyperpolarization. We studied the presence and changes of human SK1 (hSK1)- and hIK1-like immunoreactivity in control and injured human dorsal root ganglia (DRG) and peripheral nerves and their regulation by key neurotrophic factors in cultured rat sensory neurones. Using specific antibodies, hSK-1 and hIK-1-like immunoreactivity was detected in a majority of large and small/medium-sized cell bodies of human DRG. hSK1 immunoreactivity was decreased significantly in cell bodies of avulsed human DRG (n = 8, surgery delay 8 h to 12 months). There was a decrease in hIK1-like immunoreactivity predominantly in large cells acutely (<3 weeks after injury), but also in small/medium cells of chronic cases. Twenty-three injured peripheral nerves were studied (surgery delay 8 h to 12 months); in five of these, hIK1-like immunoreactivity was detected proximally but not distally to injury, whereas neurofilament staining confirmed the presence of nerve fibres in both regions. These five nerves, unlike the others, had all undergone Wallerian degeneration previously and the loss of hIK1-like immunoreactivity may therefore reflect reduced axonal transport of this ion channel across the injury site in regenerated fibres, as well as decreased expression in the cell body. In vitro studies of neonatal rat DRG neurones showed that nerve growth factor (NGF) significantly increased the percentage of hSK1-positive cells, whereas neurotrophin 3 (NT-3) and glial cell line-derived neurotrophic factor (GDNF) failed to show a significant effect. NT-3 stimulated hIK1 expression, while NGF and GDNF were ineffective. As expected, NGF increased expression of the voltage-gated sodium channel SNS1/PN3 in this system. Decreased retrograde transport of these neurotrophic factors in injured sensory neurones may thus reduce expression of these ion channels and increase excitability. Blockade of IK1-like and other potassium channels by aminopyridines (4-AP and 3,4-DAP) may also explain the paraesthesiae induced by these medications. Selective potassium channel openers are likely to represent novel therapies for pain following nerve injury.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Animals
- Animals, Newborn
- Antibodies/metabolism
- Cells, Cultured
- Female
- Ganglia, Spinal/cytology
- Ganglia, Spinal/injuries
- Ganglia, Spinal/metabolism
- Glial Cell Line-Derived Neurotrophic Factor
- Humans
- Immunohistochemistry
- Male
- Middle Aged
- Nerve Growth Factor/pharmacology
- Nerve Growth Factors
- Nerve Tissue Proteins/pharmacology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neuroprotective Agents/pharmacology
- Neurotrophin 3/pharmacology
- Peripheral Nerve Injuries
- Peripheral Nerves/metabolism
- Potassium Channels/metabolism
- Potassium Channels, Calcium-Activated
- Rats
- Rats, Wistar
- Small-Conductance Calcium-Activated Potassium Channels
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Affiliation(s)
- M K Boettger
- Peripheral Neuropathy Unit, Department of Neurology, Imperial College of Science, Technology and Medicine, Hammersmith Hospital, London, UK
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Anand U, Bastani B, Dhanraj P, Ballal SH. Intradialytic dobutamine therapy in maintenance hemodialysis patients with persistent hypotension. Am J Nephrol 1999; 19:459-63. [PMID: 10460934 DOI: 10.1159/000013498] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Intradialysis hypotension is a common problem, especially in patients with poor left-ventricular function. We studied 6 patients who were on maintenance hemodialysis with left-ventricular ejection fraction of <40%, whose dialysis sessions were often complicated with severe hypotension (systolic blood pressure <90 mm Hg). Dobutamine infusion during dialysis significantly reduced the number of hypotensive episodes, increased left-ventricular ejection fraction, and decreased the number of emergency admissions to the hospital.
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Affiliation(s)
- U Anand
- Divisions of Nephrology, Manipal Hospital, Bangalore, India
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Abstract
We report two cases of necrobiotic palisaded granulomas which developed at the site of intradermal hepatitis B vaccination. To the best of our knowledge, this kind of reaction has not been reported previously.
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Affiliation(s)
- K Ajithkumar
- Department of Dermatology, C.M.C. Hospital, Vellore, India
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Anand U, Anand CV, Chandrika C, Agarwal R. Interventional therapy with megadose of antioxidant vitamins in patients with acute myocardial infarction: could we throw caution to the winds? Am J Cardiol 1997; 80:823-4. [PMID: 9315605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Abstract
OBJECTIVE There are reports of alprazolam-induced hypomania/mania. Here is a case report of a patient who developed hypomania during treatment with alprazolam, but not with diazepam, another benzodiazepine derivative. CLINICAL PICTURE The illness was of 2 months' duration and the patient received a diagnosis of anxious depression. Following treatment with alprazolam, the patient developed hypomania characterised by euphoria, overactivity, overtalkactivity, racing thoughts, oversocialisation, enhanced self-confidence and disturbed sleep. TREATMENT Hypomania subsided when alprazolam was withdrawn. There was no recurrence with fluoxetine or diazepam that ameliorated the primary condition. OUTCOME The patient was symptom-free on follow-up. CONCLUSIONS Alprazolam can induce hypomania/mania and, perhaps, it differs from other benzodiazepines in its mode of action. Clinicians have to be alert to the possibility of their patients developing hypomania/mania while on alprazolam.
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Affiliation(s)
- J Reddy
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore, India
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Anand CV, Anand U, Agarwal R. Anti-oxidant enzymes, gamma-glutamyl transpeptidase and lipid peroxidation in kidney of rats exposed to cigarette smoke. Indian J Exp Biol 1996; 34:486-8. [PMID: 9063083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Glutathione reductase (GR), glutathione peroxidase (GSH Px) and catalase (Cat) were determined in the kidneys of rats exposed to cigarette smoke for 3 months. Activity of the brush-border enzyme gamma-glutamyl transpeptidase (GGT), glutathione (GSH) and lipid peroxide levels (LPX) were also estimated in both, kidney homogenates and urine. Activities of GR, Cat, GGT and the levels of GSH were decreased in the kidney. However, the activities of GSH Px and LPX levels were increased. Urinary excretion of GGT, GSH and LPX were also higher. Fall in the activity of GR and rise in the activity of GSH Px, may perturb the reduced glutathione/oxidised glutathione ratio, which in turn could lead to increased LPX seen in chronic cigarette smoke exposure.
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Affiliation(s)
- C V Anand
- Department of Biochemistry, MS Ramaiah Medical College, Bangalore, India
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Abstract
Developing sensory neurons interact with molecular signals in the local environment to generate stereotypic nerve pathways. Regenerating neurons seem to lose the ability to reinnervate their original sites in the targets, resulting in abnormal sensory input and consequent clinical pathophysiology. The specificity of reinnervation of peripheral targets by regenerating axons is thus crucial for normal recovery of function. In this study, we have examined evidence for selectivity of interactions between primary afferent neurons from identified levels of the spinal cord and different peripheral nerve environments by culturing these neurons on sections of nerves to muscle and viscera. We have compared the growth of a population of sensory afferents normally innervating somatic targets (dorsal root ganglion cells from L4 and L5) with populations containing many afferents innervating visceral targets (L6 and S1 dorsal root ganglia and nodose ganglion). These neurons, from newly born rats, were cultured on unfixed cryostat sections of normal and prelesioned gastrocnemius nerve, pelvic spinal nerve and vagus nerve from adult rats. Normal muscle nerve was seen to support the regeneration of a significantly greater proportion of somatic neurons, with longer neurites, than the visceral nerves. Similarly, much higher proportions of the 'visceral' population of afferent neurons were seen to extend neurites on the normal visceral nerve substrates, with longer neurites, than on the muscle nerve substrate. The selectivity displayed by the sensory neurons for their normal nerve substrates was abolished when they were cultured on prelesioned nerve substrates subjected to Wallerian degeneration, which was apparent from the equivalent and increased proportions of growing neurons having comparable neurite lengths, on all the nerve substrates. We conclude that sensory neurons recognize and respond to substrate-specific and substrate-bound molecules present in normal adult peripheral nerves, and that these differences are lost in prelesioned nerves following Wallerian degeneration.
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Affiliation(s)
- U Anand
- Division of Anatomy and Cell Biology, United Medical Dental Schools of Guy's and St. Thomas' Hospitals, London, UK
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Baranowski AP, Anand U, McMahon SB. Retrograde labelling of dorsal root ganglion cells in the rat: a quantitative and morphological comparison of Fluoro-Gold with horseradish peroxidase labelling. Neurosci Lett 1992; 141:53-6. [PMID: 1380681 DOI: 10.1016/0304-3940(92)90332-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have compared retrograde labelling of rat primary sensory neurons using Fluoro-Gold (FG) and horseradish peroxide conjugated with wheat germ agglutinin (HRP-WGA). Fluoro-Gold 2.5% after 48 h transit time and FG 5% after 24 and 48 h retrogradely labelled similar numbers of cell profiles as HRP-WGA (P greater than 0.1% Student's t-test). The calculated cell size distribution for the above FG groups were similar to those for the HRP-WGA. However, FG 2.5% after a 24 h transit time labelled significantly fewer cells (P less than 0.001 Student's t-test). FG retrograde transport may be used to identify the same population of DRG cells as HRP-WGA.
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Affiliation(s)
- A P Baranowski
- Department of Physiology, St. Thomas' Hospital Medical School, UMDS, London, UK
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Anand CV, Anand U, Sadasivudu B. Acute effects of ethanol on production & disposal of adenosine from rat myocardium. Biochem Int 1985; 10:311-7. [PMID: 2859855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adenosine is a local hormone and is considered to act as a vasodilatory substance when released locally. Alcohol is known to affect membrane structure and acts as a coronary vasodilator. Membrane enzymes such as 5'-nucleotidase, adenosine deaminase, and gammaglutamyl transpeptidase, along with AMP deaminase, have been studied in rat myocardial tissue following the administration of a sufficiently toxic dose (producing semiconsciousness) of ethanol (1ml of 7M ethanol/100g body wt.). The activity of 5'-nucleotidase as well as that of adenosine deaminase increased due to the administration of ethanol, without any significant change in the activities of gammaglutamyl transpeptidase and AMP deaminase. These changes are discussed in relation to the metabolic changes occurring in the myocardium and the resultant effects on the coronary vessels.
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