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102
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Prabhakaran R, Krishnan V, Pasumpon K, Sukanya D, Wendel E, Jayabalakrishnan C, Bertagnolli H, Natarajan K. Preparation, spectral characterization, electrochemistry, EXAFS, antibacterial and catalytic activity of new ruthenium (III) complexes containing ONS donor ligands with triphenylphosphine/arsine. Appl Organomet Chem 2006. [DOI: 10.1002/aoc.1026] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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103
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Natarajan K, Patil S, Lesley N, Ninan B. Predictors of Prolonged Mechanical Ventilation After On-pump Coronary Artery Bypass Grafting. Ann Card Anaesth 2006. [DOI: 10.4103/0971-9784.37894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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104
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Kaveri MV, Prabhakaran R, Karvembu R, Natarajan K. Synthesis and spectral studies of [RuCl(CO)(L)(PPh3)(B)] (HL = 2'-hydroxychalcones and B = PPh3, pyridine or piperidine) and their catalytic and biological applications. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:2915-8. [PMID: 16165031 DOI: 10.1016/j.saa.2004.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Accepted: 11/01/2004] [Indexed: 05/04/2023]
Abstract
The reactions of [RuHCl(CO)(PPh3)2(B)] (B = PPh3, pyridine or piperidine) and 2'-hydroxychalcones led to the formation of [RuCl(CO)(PPh3)(L)(B)] (L = chalconate). The new complexes have been characterized by analytical and spectral (IR, electronic, 1H NMR and 31P NMR) data. They have been assigned an octahedral structure. The complexes have been used as catalysts for the aerial oxidation of cinnamyl alcohol. Some of the complexes have been tested in vitro for growth inhibitory activity against the bacteria E. coli, S. typhi and Pseudomonas sp. and the fungi A. fumigatus.
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Kameswaran M, Kumar RSA, Murali S, Natarajan K, Krishnan V. Cochlear implantation in ossified cochlea—Merf experience. Indian J Otolaryngol Head Neck Surg 2005; 57:327-9. [DOI: 10.1007/bf02907702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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106
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107
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Prabhakaran R, Geetha A, Thilagavathi M, Karvembu R, Krishnan V, Bertagnolli H, Natarajan K. Synthesis, characterization, EXAFS investigation and antibacterial activities of new ruthenium(III) complexes containing tetradentate Schiff base. J Inorg Biochem 2005; 98:2131-40. [PMID: 15541503 DOI: 10.1016/j.jinorgbio.2004.09.020] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2004] [Revised: 09/19/2004] [Accepted: 09/24/2004] [Indexed: 11/25/2022]
Abstract
A series of new hexa-coordinated ruthenium(III) complexes of the type [Ru(X)(2-atmp-ba)(EPh3)] (where H2-2-atmp-ba=N,N'-bis(2-aminothiophenol)benzoylacetone; X=Cl or Br; E=P or As) have been prepared by reacting [RuX3(EPh3)3] (where X=Cl or Br; E=P or As) with tetradentate Schiff base ligand (H2-2-atmp-ba) in 1:1 molar ratio. The complexes have been characterized by elemental analyses, Infra red, electronic, electron paramagnetic resonance spectroscopy and cyclic voltammetry. In order to confirm the coordination and structure of the complexes extended X-ray absorption fine structure spectroscopy (EXAFS) studies have been carried out. Based on the above data, an octahedral structure has been confirmed for the complexes. The new complexes were also screened for their antibacterial properties.
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Prasher V, Cumella S, Natarajan K, Rolfe E, Shah S, Haque MS. Magnetic resonance imaging, Down's syndrome and Alzheimer's disease: research and clinical implications. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2003; 47:90-100. [PMID: 12542574 DOI: 10.1046/j.1365-2788.2003.00445.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
BACKGROUND The diagnosis of Alzheimer's disease (AD) remains at times difficult to make using available neuropsychological measures. Neuro-imaging is a relatively new form of detecting the changes associated with dementia. The present study investigated the role of magnetic resonance imaging (MRI) in diagnosing AD in adults with Down's syndrome (DS). METHODS Subjects with DS and Alzheimer-type dementia were matched to non-demented controls with DS. Magnetic resonance imaging findings (i.e. volumetric and two-dimensional scans) were compared between the two groups in order to show a relationship between the changes of AD and structural MRI abnormalities. RESULTS Specific structural abnormalities which are seen in non-intellectually disabled subjects with dementia are also found in individuals with both DS and AD. However, such findings cannot be used to diagnose clinical AD with good accuracy in adults with DS. A number of practical issues of patient compliance and over-sedation are demonstrated by the findings. CONCLUSIONS Magnetic resonance imaging has an important but limited role to play in the management of AD in the population with DS. If intravenous sedation is used, medical support is essential to prevent a serious mishap.
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Jayabalakrishnan C, Karvembu R, Natarajan K. Ruthenium(III) Schiff Base Complexes: Catalytic Activity in Aryl–Aryl Coupling Reaction and Antimicrobial Activity. ACTA ACUST UNITED AC 2003. [DOI: 10.1081/sim-120025439] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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110
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Jayabalakrishnan C, Karvembu R, Natarajan K. SYNTHESIS, CHARACTERISATION, CATALYTIC, AND BIOCIDAL STUDIES OF RUTHENIUM(III) COMPLEXES WITH THIOSEMICARBAZONES OF β-DIKETOESTERS. ACTA ACUST UNITED AC 2002. [DOI: 10.1081/sim-120013023] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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111
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Thangadurai TD, Anitha D, Natarajan K. SYNTHESIS AND BIOLOGICAL ACTIVITY OF RUTHENIUM(II) CARBONYL COMPLEXES CONTAINING TETRADENTATE SCHIFF BASES. ACTA ACUST UNITED AC 2002. [DOI: 10.1081/sim-120014309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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112
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Daniel Thangadurai T, Gowri M, Natarajan K. SYNTHESIS AND CHARACTERISATION OF RUTHENIUM(III) COMPLEXES CONTAINING MONOBASIC BIDENTATE SCHIFF BASES AND THEIR BIOLOGICAL ACTIVITIES. ACTA ACUST UNITED AC 2002. [DOI: 10.1081/sim-120003211] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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113
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Prakash MVS, Radhakrishnan M, Yogeshwari A, Nazir W, Maragatham K, Natarajan K. Inverse Marcus Gunn phenomenon. Indian J Ophthalmol 2002; 50:142-4. [PMID: 12194575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
Inverse Marcus-Gunn phenomenon is very rare. It is usually acquired. We report a young male patient presenting with congenital ptosis and inverse Marcus-Gunn phenomenon.
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Sahoo NC, Rao KVS, Natarajan K. CD80 expression is induced on activated B cells following stimulation by CD86. Scand J Immunol 2002; 55:577-84. [PMID: 12028560 DOI: 10.1046/j.1365-3083.2002.01093.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We examined the effects of CD86 ligation on surface densities of CD80 on activated B cells. For this, splenic B cells where CD86 levels had been enhanced upon anti-immunoglobulin M (IgM) treatment were employed. Incubation of such CD86-expressing B cells with anti-CD86 monoclonal antibody (MoAb) resulted in a marked upregulation in cell surface levels of CD80. Such an enhancement in surface levels was also accompanied by a marked increase in CD80 mRNA, suggesting that the effects of CD86-triggering are exerted at the level of CD80 message. Furthermore, coculture of CD86-upregulated B cells with CD28-expressing fibroblasts also led to the enhancement of CD80 levels, which was not obtained upon incubation with cells expressing cytotoxic T-lymphocyte-associated molecule (CTLA)-4-Ig. Finally, we also demonstrate that CD86-induced CD80 is fully competent to function as a costimulatory molecule, as revealed by its ability to enhance cytokine secretion by allogeneic T cells. Thus, these results reveal the existence of another pathway that regulates the expression of CD80, at least on activated B cells, which could have important implications in directing the course of an immune response.
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Bhujwalla ZM, Artemov D, Aboagye E, Ackerstaff E, Gillies RJ, Natarajan K, Solaiyappan M. The physiological environment in cancer vascularization, invasion and metastasis. NOVARTIS FOUNDATION SYMPOSIUM 2002; 240:23-38; discussion 38-45, 152-3. [PMID: 11727932 DOI: 10.1002/0470868716.ch3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
One of the most lethal aspects of cancer arises from its ability to invade and metastasize. Determining the factors that promote cancer cell invasion and metastasis is therefore critically important in treating this disease. The tumour physiological environment is uniquely different from normal tissue, and exhibits hypoxia, acidic extracellular pH and high levels of lactate. This environment, dictated largely by abnormal tumour vasculature and metabolism, in turn also promotes angiogenesis. The physiological environment, tumour metabolism, angiogenesis and vascularization are therefore inextricably linked. We have developed and applied non-invasive magnetic resonance (MR) imaging (I) and spectroscopy (S) techniques to understand the role of vascular, physiological and metabolic properties in cancer invasion and metastasis. These MR studies are performed with human breast and prostate cancer cells maintained in culture or grown as solid tumours in immune-suppressed mice. We have detected significant differences in vascular, physiological and metabolic characteristics of metastatic and non-metastatic human breast and prostate cancer models with MRI and MRS. Using a combined MRI/MRS approach we are currently acquiring metabolic, extracellular pH and vascular images from the same localized regions within a solid tumour to further understand the dynamics between these parameters and their role in cancer invasion and metastasis.
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Adams RD, Babin JE, Natarajan K. Pentacoordinate bridging sulfido ligand in a square-pyramidal geometry. The synthesis and crystal and molecular structure of Os5(CO)15(.mu.5-S)[W(CO)4(PPh3)]. J Am Chem Soc 2002. [DOI: 10.1021/ja00272a063] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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117
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Adams RD, Horvath IT, Natarajan K. Ligand substitution reactions in electron-rich clusters. The synthesis, structures, and bonding of Os4(CO)12L(.mu.3-S)2 and Os4(CO)11L(.mu.3-S)2 (L = PMe2Ph and CN-t-Bu). Organometallics 2002. [DOI: 10.1021/om00088a016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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118
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Natarajan K, Shepard LA, Chodosh J. The use of DNA array technology in studies of ocular viral pathogenesis. DNA Cell Biol 2002; 21:483-90. [PMID: 12167252 DOI: 10.1089/10445490260099782] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
DNA arrays can be used to simultaneously analyze the expression of hundreds of genes and permit systematic approaches to biological discovery with a potentially profound impact on genomics, pharmacogenomics, and proteomics. Microarrays have been used to study host-pathogen interactions, and recently this technology has been applied to investigate host-virus interactions. DNA arrays are used to monitor host alterations in several virus-induced cancers and upon infection with wild-type or modified viruses, or viral gene products. Alternatively, viral chips are used to characterize the transcriptional program of pathogenic viruses and in antiviral drug screening and drug resistance. With an aim to extend the use of this technology to ocular research, and specifically to study changes in host cell transcription in ocular adenovirus infection, we used a commercial array to compare adenovirus-infected human corneal cells to mock-infected cells. Of the 1176 genes analyzed, 72 genes associated with cell cycle regulation, apoptosis, oncogenesis, transcription, signaling, and inflammation were differentially regulated. In this review we summarize the use of DNA arrays in the study of viral infections and suggest potential uses of the technology in ocular viral pathogenesis research.
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Adams RD, Babin JE, Natarajan K, Tasi M, Wang JG. Cluster synthesis. 15. Square-pyramidal coordination of sulfur in metal cluster complexes. Synthesis and structural characterizations of Ru4(CO)7(.mu.-CO)2(PMe2Ph)2(.mu.4-S)(.mu.5-S)[W(CO)4PMe2Ph] and Os5(CO)15(.mu.5-S)[W(CO)4PPh3]. Inorg Chem 2002. [DOI: 10.1021/ic00269a018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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120
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Adams RD, Babin JE, Mathur P, Natarajan K, Wang JG. Cluster synthesis. 25. Synthesis and characterization of new mixed-metal cluster complexes by metal-metal exchange. Reactions of the sulfido cluster complexes M3(CO)9(.mu.3-CO)(.mu.3-S) (M = iron, ruthenium and osmium) with W(CO)5L (L = CO or PMe2Ph). Inorg Chem 2002. [DOI: 10.1021/ic00307a005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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121
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Shevach EM, McHugh RS, Thornton AM, Piccirillo C, Natarajan K, Margulies DH. Control of autoimmunity by regulatory T cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 490:21-32. [PMID: 11505971 DOI: 10.1007/978-1-4615-1243-1_3] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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122
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Karvembu R, Natarajan K. Synthesis and spectral studies of binuclear ruthenium(II) carbonyl complexes containing bis(β-diketone) and their applications. Polyhedron 2002. [DOI: 10.1016/s0277-5387(01)00980-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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123
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Azam M, Kesarwani M, Natarajan K, Datta A. A secretion signal is present in the Collybia velutipes oxalate decarboxylase gene. Biochem Biophys Res Commun 2001; 289:807-12. [PMID: 11735117 DOI: 10.1006/bbrc.2001.6049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The oxalate decarboxylase (OXDC) gene from Collybia velutipes is overexpressed as an active form in Schizosaccharomyces pombe. The recombinant enzyme shows similar pH optima and stability, while substrate kinetic analysis shows a ninefold decrease in K(m) value with respect to native OXDC. Most of the expressed protein was present in periplasm and remained firmly bound to cell-wall materials. However, 20% of enzyme expressed was secreted out into the medium suggesting the presence of a secretion signal (C. velutipes) in the oxalate decarboxylase gene. This secretion signal is associated with the N-terminal of OXDC as is evident by secretion of nonsecretory genes AmA1 and beta-galactosidase. An expression vector using this signal is constructed for expression and secretion of heterologous proteins in S. pombe.
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Natarajan K, Sahoo NC, Rao KV. Signal thresholds and modular synergy during expression of costimulatory molecules in B lymphocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:114-22. [PMID: 11418639 DOI: 10.4049/jimmunol.167.1.114] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We analyzed intracellular pathways modulating surface densities of CD80 and CD86 in B cells activated through ligation of the Ag receptor, and the adhesion molecule CD54. Whereas B cell Ag receptor (BCR) cross-linking alone stimulated increased expression of CD86, up-regulation of CD80 required dual stimulation with anti-IgM and anti-CD54. The principal downstream component contributed by BCR signaling, toward both CD80 and CD86 induction, was the elevated concentration of free cytoplasmic Ca(2+), recruited by way of capacitative influx. This alone was sufficient to generate an increase in CD86 levels. However, CD80 enhancement required the concerted action of both intracellular Ca(2+) concentration and CD54-initiated pathways. The nexus between anti-IgM and anti-CD54 stimulation, in the context of CD80 regulation, was identified to involve a self-propagating process of sequential synergy. The first step involved amplified accumulation of intracellular cAMP, as a result of cross-talk between BCR-mobilized Ca(2+) and CD54-derived signals. This then facilitated a second synergistic interaction between Ca(2+) and cAMP, culminating in CD80 expression. Our findings of distinct signal transducer requirements, with the added consequences of cross-talk, offers an explanation for variable modulation of costimulatory molecule expression in response to diverse physiological stimuli. Importantly, these results also reveal how concentration threshold barriers for recruitment of individual second messengers can be overcome by constructive convergence of signaling modules.
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125
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McHugh RS, Shevach EM, Margulies DH, Natarajan K. A T cell receptor transgenic model of severe, spontaneous organ-specific autoimmunity. Eur J Immunol 2001; 31:2094-103. [PMID: 11449363 DOI: 10.1002/1521-4141(200107)31:7<2094::aid-immu2094>3.0.co;2-s] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The development of mouse models of human organ-specific autoimmune diseases has been hampered by the need to immunize mice with autoantigens in potent adjuvants. Even autoantigen-specific T cell receptor transgenic models of autoimmunity have proven to be complex as the transgenic mice frequently fail to develop disease spontaneously. We have isolated a CD4(+) T cell clone (TxA23)that recognizes the gastric parietal cell antigen, H/K ATPase alpha-chain(630-641), from a mouse with autoimmune gastritis that developed after thymectomy on day 3 of life. The T cell receptor alpha and beta genes from this clone were used to generate A23 transgenic mice. All A23 transgenic animals spontaneously developed severe autoimmune gastritis, and evidence of disease was detected as early as day 10 of life. Gastritis could be transferred to immunocompromised mice with a limited number of transgenic thymocytes (10(3)), but as many as 10(7) induced only mild disease in wild-type animals. Due to the complete penetrance of spontaneous disease, identity of the auto-antigen, susceptibility to immunoregulation, and close relation to autoimmune gastritis in man, A23 transgenic mice represent a unique CD4(+) T cell-mediated disease model for understanding the multiple factors regulating organ-specific autoimmunity.
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