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Bhade SPD, Reddy PJ, Narayanan A, Narayan KK, Babu DAR, Sharma DN. Standardization of calibration procedures for quantification of gross alpha and gross beta activities using liquid scintillation counter. J Radioanal Nucl Chem 2010. [DOI: 10.1007/s10967-010-0522-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Palthi A, Narayanan A, Thakur M. Photo-induced Charge-transfer and Photovoltaic Effect in a Composite Involving a Nonconjugated Conductive Polymer and C60. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2010. [DOI: 10.1080/10601320903539348] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Reddy P, Bhade S, Narayan K, Narayanan A, Babu D, Sharma D. Comparative study of different methods for the activity quantification of 3H and 14C radionuclides in dual labeled samples using liquid scintillation analyzer. Appl Radiat Isot 2009; 67:1945-51. [DOI: 10.1016/j.apradiso.2009.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 06/01/2009] [Accepted: 07/03/2009] [Indexed: 11/29/2022]
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Narayanan A, Thorburn K, Baines P. Autopsies in children continue to reveal unanticipated discrepancies between autopsy findings and antemortem clinical diagnoses. Arch Dis Child 2009; 94:645. [PMID: 19628884 DOI: 10.1136/adc.2008.150417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Narayanan A, Palthi A, Thakur M. Electrical and Optical Properties of a Novel Nonconjugated Conductive Polymer, Polynorbornene. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2009. [DOI: 10.1080/10601320902732654] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tangri VK, Mohan S, Narayanan A, Narayan KK. Measurement and Monitoring of Tritium and Other Critical Issues in Lead Lithium Ceramic Breeder (LLCB). FUSION SCIENCE AND TECHNOLOGY 2008. [DOI: 10.13182/fst08-a1776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chatterjee S, Narayanan A. A NEW APPROACH TO DISCRIMINATION AND CLASSIFICATION USING A HAUSDORFF TYPE DISTANCE. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1467-842x.1992.tb01055.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Campbell JL, Richards SH, Dickens A, Greco M, Narayanan A, Brearley S. Assessing the professional performance of UK doctors: an evaluation of the utility of the General Medical Council patient and colleague questionnaires. Qual Saf Health Care 2008; 17:187-93. [DOI: 10.1136/qshc.2007.024679] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Baskaradoss J, Clement R, Narayanan A. Prevalence of dental fluorosis and associated risk factors in 11-15 year old school children of Kanyakumari District, Tamilnadu, India: A cross sectional survey. Indian J Dent Res 2008; 19:297-303. [DOI: 10.4103/0970-9290.44531] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Narayanan A, Ramamurthy V, Duin E, Thakur M. EPR Spectroscopic Studies of Radical Cations in a Novel Nonconjugated Conductive Polymer, Poly(β‐pinene). JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2007. [DOI: 10.1080/10601320701787016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Narayanan A. Small sample properties of parameter estimation in the dirichlet distribution. COMMUN STAT-SIMUL C 2007. [DOI: 10.1080/03610919108812976] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Narayanan A, O'Brien M, Rajput RS, Sundararaman S. Use of a Vaginal Speculum to Assist Difficult Urethral Catheterisation. Ann R Coll Surg Engl 2007. [DOI: 10.1308/rcsann.2007.89.3.316b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Patel U, Narayanan A, Singh H, Wikramanayake T, Khanna A, Niranjan S. 20 SYMPTOMATIC BRADYARRHYTHMIA LIKELY RELATED TO USE OF HERBAL MEDICINE. J Investig Med 2005. [DOI: 10.2310/6650.2005.00006.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Narayanan A, Keedwell E, Gamalielsson J, Tatineni S. Single-layer artificial neural networks for gene expression analysis. Neurocomputing 2004. [DOI: 10.1016/j.neucom.2003.10.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Narayanan A, Aradhya S. Oral health status and treatment requirements of (3-5) years old pre-school children in Bangalore City-A survey. JOURNAL OF INDIAN ASSOCIATION OF PUBLIC HEALTH DENTISTRY 2002. [DOI: 10.4103/2319-5932.175190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
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Lukowiak AA, Narayanan A, Li ZH, Terns RM, Terns MP. The snoRNA domain of vertebrate telomerase RNA functions to localize the RNA within the nucleus. RNA (NEW YORK, N.Y.) 2001; 7:1833-1844. [PMID: 11780638 PMCID: PMC1370221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Telomerase RNA is an essential component of the ribonucleoprotein enzyme involved in telomere length maintenance, a process implicated in cellular senescence and cancer. Vertebrate telomerase RNAs contain a box H/ACA snoRNA motif that is not required for telomerase activity in vitro but is essential in vivo. Using the Xenopus oocyte system, we have found that the box H/ACA motif functions in the subcellular localization of telomerase RNA. We have characterized the transport and biogenesis of telomerase RNA by injecting labeled wild-type and variant RNAs into Xenopus oocytes and assaying nucleocytoplasmic distribution, intranuclear localization, modification, and protein binding. Although yeast telomerase RNA shares characteristics of spliceosomal snRNAs, we show that human telomerase RNA is not associated with Sm proteins or efficiently imported into the nucleus. In contrast, the transport properties of vertebrate telomerase RNA resemble those of snoRNAs; telomerase RNA is retained in the nucleus and targeted to nucleoli. Furthermore, both nuclear retention and nucleolar localization depend on the box H/ACA motif. Our findings suggest that the H/ACA motif confers functional localization of vertebrate telomerase RNAs to the nucleus, the compartment where telomeres are synthesized. We have also found that telomerase RNA localizes to Cajal bodies, intranuclear structures where it is thought that assembly of various cellular RNPs takes place. Our results identify the Cajal body as a potential site of telomerase RNP biogenesis.
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Augusti KT, Narayanan A, Pillai LS, Ebrahim RS, Sivadasan R, Sindhu KR, Subha I, Abdeen S, Nair SS. Beneficial effects of garlic (Allium sativum Linn) on rats fed with diets containing cholesterol and either of the oil seeds, coconuts or groundnuts. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 2001; 39:660-7. [PMID: 12019759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Feeding of 2% cholesterol diet increased lipid parameters in serum and tissues of rats during a period of one month. In addition to the above, lipid peroxidation also increased and activities of certain enzymes were significantly altered in the tissues. Similar changes were also observed to a greater extent with diets containing 40% by weight of coconut kernel or groundnut with and without 2% cholesterol. The enzymes studied were HMGCoA reductase, AST, ALT and ALP in tissues and serum as the case may be. In general the atherogenic effects were observed more with groundnut containing diets than those with coconut. Even though the oil from the former is mostly unsaturated and that from the latter is mostly saturated, these analytical criteria do not relate to their atherogenic effects. When 5% garlic was incorporated with any of the high fat diets, the lipid parameters, their peroxidation and alterations in enzyme activities were significantly decreased. These results show that garlic contains some principles that counteract the atherogenicity of the above oil seeds.
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Yu YT, Shu MD, Narayanan A, Terns RM, Terns MP, Steitz JA. Internal modification of U2 small nuclear (sn)RNA occurs in nucleoli of Xenopus oocytes. J Cell Biol 2001; 152:1279-88. [PMID: 11257127 PMCID: PMC2199211 DOI: 10.1083/jcb.152.6.1279] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
U2 small nuclear (sn)RNA contains a large number of posttranscriptionally modified nucleotides, including a 5' trimethylated guanosine cap, 13 pseudouridines, and 10 2'-O-methylated residues. Using Xenopus oocytes, we demonstrated previously that at least some of these modified nucleotides are essential for biogenesis of a functional snRNP. Here we address the subcellular site of U2 internal modification. Upon injection into the cytoplasm of oocytes, G-capped U2 that is transported to the nucleus becomes modified, whereas A-capped U2 that remains in the cytoplasm is not modified. Furthermore, by injecting U2 RNA into isolated nuclei or enucleated oocytes, we observe that U2 internal modifications occur exclusively in the nucleus. Analysis of the intranuclear localization of fluorescently labeled RNAs shows that injected wild-type U2 becomes localized to nucleoli and Cajal bodies. Both internal modification and nucleolar localization of U2 are dependent on the Sm binding site. An Sm-mutant U2 is targeted only to Cajal bodies. The Sm binding site can be replaced by a nucleolar localization signal derived from small nucleolar RNAs (the box C/D motif), resulting in rescue of internal modification as well as nucleolar localization. Analysis of additional chimeric U2 RNAs reveals a correlation between internal modification and nucleolar localization. Together, our results suggest that U2 internal modification occurs within the nucleolus.
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Parker DA, Marino V, Krishna M, Narayanan A, de la Lande IS. Failure of presynaptic purinoceptors to modulate noradrenaline release from sympathetic nerves in human dental pulp. Arch Oral Biol 2000; 45:827-31. [PMID: 10973556 DOI: 10.1016/s0003-9969(00)00059-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effects of putative presynaptic P1- and/or P2-purinoceptors on the release of noradrenaline from sympathetic nerves in human dental pulp were examined by testing the effects of agonists and an antagonist of these receptors on the stimulation-induced overflow of [(3)H]noradrenaline from tissue treated with desipramine (0.3 micromol/l) and preincubated with [(3)H]noradrenaline (0.6 micromol/l). The P1-purinoceptor agonists adenosine (1.0 mmol/l) and 2-chloroadenosine (0.01-1.0 mmol/l) and the antagonist 8-cyclopentyl-1,3-dipropyl xanthine (1.0 micromol/l), and the P2-purinoceptor agonists ATP (0.1 mmol/l) and beta, gamma-methylene-ATP (0.01 mmol/l), did not modulate the release of noradrenaline. Adenosine was also without effect in dental pulp treated with the alpha(2)-adrenoceptor antagonist rauwolscine. It is concluded that presynaptic P1-purinoceptors and those P2-purinoceptors activated by adenine nucleotides are either not present on sympathetic nerves in human dental pulp or that they exert little or no effect on the release of noradrenaline.
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Speckmann W, Narayanan A, Terns R, Terns MP. Nuclear retention elements of U3 small nucleolar RNA. Mol Cell Biol 1999; 19:8412-21. [PMID: 10567566 PMCID: PMC84939 DOI: 10.1128/mcb.19.12.8412] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The processing and methylation of precursor rRNA is mediated by the box C/D small nucleolar RNAs (snoRNAs). These snoRNAs differ from most cellular RNAs in that they are not exported to the cytoplasm. Instead, these RNAs are actively retained in the nucleus where they assemble with proteins into mature small nucleolar ribonucleoprotein particles and are targeted to their intranuclear site of action, the nucleolus. In this study, we have identified the cis-acting sequences responsible for the nuclear retention of U3 box C/D snoRNA by analyzing the nucleocytoplasmic distributions of an extensive panel of U3 RNA variants after injection of the RNAs into Xenopus oocyte nuclei. Our data indicate the importance of two conserved sequence motifs in retaining U3 RNA in the nucleus. The first motif is comprised of the conserved box C' and box D sequences that characterize the box C/D family. The second motif contains conserved box sequences B and C. Either motif is sufficient for nuclear retention, but disruption of both motifs leads to mislocalization of the RNAs to the cytoplasm. Variant RNAs that are not retained also lack 5' cap hypermethylation and fail to associate with fibrillarin. Furthermore, our results indicate that nuclear retention of U3 RNA does not simply reflect its nucleolar localization. A fragment of U3 containing the box B/C motif is not localized to nucleoli but retained in coiled bodies. Thus, nuclear retention and nucleolar localization are distinct processes with differing sequence requirements.
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Narayanan A, Lukowiak A, Jády BE, Dragon F, Kiss T, Terns RM, Terns MP. Nucleolar localization signals of box H/ACA small nucleolar RNAs. EMBO J 1999; 18:5120-30. [PMID: 10487763 PMCID: PMC1171582 DOI: 10.1093/emboj/18.18.5120] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The two major families of small nucleolar RNAs (snoRNAs), Box C/D and Box H/ACA, are generated in the nucleoplasm and transported to the nucleolus where they function in rRNA processing and modification. We have investigated the sequences involved in the intranuclear transport of Box H/ACA snoRNAs by assaying the localization of injected fluorescent RNAs in Xenopus oocyte nuclear spreads. Our analysis of U17, U64 and U65 has revealed that disruption of either of the conserved sequence elements, Box H or Box ACA, eliminates nucleolar localization. In addition, the stem present at the base of the 3' hairpin is required for efficient nucleolar localization of U65. Fragments or rearrangements of U65 that consist of Box H and Box ACA flanking either the 5' or 3' hairpin are targeted to the nucleolus. The targeting is dependent on the presence of the Box sequences, but not on their orientation. Our results indicate that in each of the two major families of snoRNAs, a motif composed of the signature conserved sequences and an adjacent structural element that tethers the sequence elements directs the nucleolar localization of the RNAs. We demonstrate that telomerase RNA is also targeted to the nucleolus by a Box ACA-dependent mechanism.
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Narayanan A, Speckmann W, Terns R, Terns MP. Role of the box C/D motif in localization of small nucleolar RNAs to coiled bodies and nucleoli. Mol Biol Cell 1999; 10:2131-47. [PMID: 10397754 PMCID: PMC25425 DOI: 10.1091/mbc.10.7.2131] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Small nucleolar RNAs (snoRNAs) are a large family of eukaryotic RNAs that function within the nucleolus in the biogenesis of ribosomes. One major class of snoRNAs is the box C/D snoRNAs named for their conserved box C and box D sequence elements. We have investigated the involvement of cis-acting sequences and intranuclear structures in the localization of box C/D snoRNAs to the nucleolus by assaying the intranuclear distribution of fluorescently labeled U3, U8, and U14 snoRNAs injected into Xenopus oocyte nuclei. Analysis of an extensive panel of U3 RNA variants showed that the box C/D motif, comprised of box C', box D, and the 3' terminal stem of U3, is necessary and sufficient for the nucleolar localization of U3 snoRNA. Disruption of the elements of the box C/D motif of U8 and U14 snoRNAs also prevented nucleolar localization, indicating that all box C/D snoRNAs use a common nucleolar-targeting mechanism. Finally, we found that wild-type box C/D snoRNAs transiently associate with coiled bodies before they localize to nucleoli and that variant RNAs that lack an intact box C/D motif are detained within coiled bodies. These results suggest that coiled bodies play a role in the biogenesis and/or intranuclear transport of box C/D snoRNAs.
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Mathew S, Narayanan A, Segaran R, Paramasivan CN. Early results from indirect drug susceptibility test for tubercle bacilli. Indian J Med Res 1999; 109:167-9. [PMID: 10643140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
The indirect susceptibility test results on L-J medium for tubercle bacilli against streptomycin, isoniazid and rifampicin were read at the end of 2 wk and compared with the results at 4 wk. It was found that drug resistance could be correctly predicted in over 70 per cent of cultures including multi-drug resistant tuberculosis (MDR TB) strains at the end of 2 wk. The susceptibility to para-nitrobenzoic acid (PNB) read at 2 wk was able to distinguish non-tuberculous mycobacteria from Mycobacterium tuberculosis cultures. The early detection of resistance by this procedure requires only minimum inputs, and can benefit the majority of patients harbouring drug resistant tubercle bacilli.
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Gelderloos CJ, Alexander JM, Boger J, Magda MT, Narayanan A, DeYoung PA, Elmaani A, McMahan MA. Classical tests for statistical evaporation at 680 MeV 40Ar+natAg. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1996; 54:3056-3061. [PMID: 9971678 DOI: 10.1103/physrevc.54.3056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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