51
|
Reddy MM, Deighton M, Gupta RK, Bhattacharya SN, Parthasarathy R. Biodegradation of oxo-biodegradable polyethylene. J Appl Polym Sci 2009. [DOI: 10.1002/app.29073] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
52
|
|
53
|
Parthasarathy R, Palli SR. Molecular analysis of juvenile hormone analog action in controlling the metamorphosis of the red flour beetle, Tribolium castaneum. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2009; 70:57-70. [PMID: 19072925 PMCID: PMC3556276 DOI: 10.1002/arch.20288] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The juvenile hormone analogs (JHA) are known to disrupt insect development but the molecular mechanisms of their action have been studied only in a few model insects belonging to orders Diptera and Lepidoptera. Here, we investigated the mechanisms of JHA action in red flour beetle, Tribolium castaneum, belonging to the order Coleoptera. Application of JHA during penultimate and final instar larval stages blocked larval-pupal metamorphosis and induced supernumerary larval molts. When compared to the control insects undergoing larval-pupal molt, down-regulation of expression of transcription factor, Broad, and up-regulation of other genes involved in 20-hydroxyecdysone (20E) action (FTZ-F1, E74) were observed in JHA-treated larvae undergoing supernumerary larval molts. The presence of JHA during the final instar larval stage blocked the midgut remodeling wherein programmed cell death (PCD) of larval cells and proliferation and differentiation of imaginal cells to pupal gut epithelium were impaired. The comparative analysis of 20E-induced gene expression in the midguts of JHA-treated and control insects revealed that JHA suppressed the expression of EcRA, EcRB, Broad, E74, E75A, and E75B, resulting in a block in PCD as well as proliferation and differentiation of imaginal cells.
Collapse
|
54
|
Abstract
The objective of this study was to examine the coping patterns followed by the junior college students. Further, an extensive effort was done to study the gender differences in coping patterns used by the students. This study was conducted in Christ College, Bangalore and on the first and second-year students of pre-university studying in either of the branches (Bachelor of Arts, Science, or Commerce). A total of 120 samples were collected from study population of junior college students using the random sampling method. The sample comprised, 40 students from each group of Arts, Science, and Commerce, including both of the sexes. The tools such as, socio-demographic data sheet and coping checklist, were used. The study findings revealed that majority of the students adopted emotion- and problem-focused coping strategies. Most of the female students adopted emotion-focused coping strategies, whereas the male students mostly used problem-focused coping strategies.
Collapse
|
55
|
Parthasarathy R, Palli SR. Proliferation and differentiation of intestinal stem cells during metamorphosis of the red flour beetle,Tribolium castaneum. Dev Dyn 2008; 237:893-908. [DOI: 10.1002/dvdy.21475] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
|
56
|
Parthasarathy R, Tan A, Palli SR. bHLH-PAS family transcription factor methoprene-tolerant plays a key role in JH action in preventing the premature development of adult structures during larval-pupal metamorphosis. Mech Dev 2008; 125:601-16. [PMID: 18450431 DOI: 10.1016/j.mod.2008.03.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 03/14/2008] [Accepted: 03/15/2008] [Indexed: 11/18/2022]
Abstract
The biological actions of juvenile hormones are well studied; they regulate almost all aspects of an insect's life. However, the molecular actions of these hormones are not well understood. Recent studies in the red flour beetle, Tribolium castaneum, demonstrated the utility of this insect as a model system to study JH action. These studies confirmed that the bHLH-PAS family transcription factor, methoprene-tolerant (TcMet,) plays a key role in JH action during larval stages. In this study, we investigated the role of TcMet in JH action during larval-pupal metamorphosis. The phenotypes of TcMet RNAi insects shared similarity with the phenotypes of some allatectomized lepidopteran larvae that were attempting to undergo precocious larval-pupal metamorphosis. Knocking-down TcMet during the final instar also disrupted larval-pupal ecdysis, resulting in the development of adultoid underneath the larval skin. However, the loss of TcMet did not completely block remodeling of internal tissues such as midgut. T. castaneum larvae injected with TcMet dsRNA demonstrated a resistance to a JH analog (JHA), hydroprene, irrespective of time and route of application. Knocking-down TcMet also caused down regulation of JH-response genes, JHE and Kr-h1 suggesting that TcMet might be involved in the expression of these genes. Based on the phenotype, gene expression, and JHA action studies in TcMet RNAi insects, this study concludes that Met plays a key role in JH action for preventing the premature development of adult structures during larval-pupal metamorphosis.
Collapse
|
57
|
Parthasarathy R, Tan A, Bai H, Palli SR. Transcription factor broad suppresses precocious development of adult structures during larval-pupal metamorphosis in the red flour beetle, Tribolium castaneum. Mech Dev 2007; 125:299-313. [PMID: 18083350 DOI: 10.1016/j.mod.2007.11.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/05/2007] [Accepted: 11/06/2007] [Indexed: 11/18/2022]
Abstract
Broad (br), a transcription factor containing the Broad-Tramtrack-Bric-a-brac (BTB) and zinc finger domains was shown to mediate 20-hydroxyecdysone (20E) action and pupal development in Drosophila melanogaster and Manduca sexta. We determined the key roles of br during larval-pupal metamorphosis using RNA interference (RNAi) in a coleopteran insect, Tribolium castaneum. Two major peaks of T. castaneum broad (Tcbr) mRNA, one peak at the end of feeding stage prior to the larvae entering the quiescent stage and another peak during the quiescent stage were detected in the whole body and midgut tissue dissected from staged insects. Expression of br during the final instar larval stage is essential for successful larval-pupal metamorphosis, because, RNAi-mediated knock-down of Tcbr during this stage derailed larval-pupal metamorphosis and produced insects that showed larval, pupal and adult structures. Tcbr dsRNA injected into the final instar larvae caused reduction in the mRNA levels of genes known to be involved in 20E action (EcRA, E74 and E75B). Tcbr dsRNA injected into the final instar larvae also caused an increase in the mRNA levels of JH-response genes (JHE and Kr-h1b). Knock-down of Tcbr expression also affected 20E-mediated remodeling of midgut during larval-pupal metamorphosis. These data suggest that the expression of Tcbr during the final instar larval stage promotes pupal program while suppressing the larval and adult programs ensuring a transitory pupal stage in holometabolous insects.
Collapse
|
58
|
Singh A, Kango-Singh M, Parthasarathy R, Gopinathan KP. Larval legs of mulberry silkworm Bombyx mori are prototypes for the adult legs. Genesis 2007; 45:169-76. [PMID: 17417803 DOI: 10.1002/dvg.20280] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Morphological diversity of leg appendages is one of the hallmarks of developmental evolution. Limbs in insects may develop either from their embryonic prototypes or from imaginal discs harbored inside the larva. Bombyx mori (B. mori), a Lepidopteran insect, develops adult wings from larval wing imaginal discs. However, it has been debated whether the adult legs of B. mori arise from imaginal discs or from the larval legs. Here we addressed how the larval legs relate to their adult counterparts. We present the morphological landmarks during early leg development. We used expression of developmental genes like Distalless and extradenticle to mark leg primordia. Finally, we employed classical excision approach to develop a fate map of the adult leg. Excision and ablation of thoracic legs along proximo-distal axis at various times during larval development resulted in the loss of corresponding adult leg segments. Our data suggest that B. mori legs develop from larval appendages rather than leg imaginal discs.
Collapse
|
59
|
Parthasarathy R, Palli SR. Stage- and cell-specific expression of ecdysone receptors and ecdysone-induced transcription factors during midgut remodeling in the yellow fever mosquito, Aedes aegypti. JOURNAL OF INSECT PHYSIOLOGY 2007; 53:216-29. [PMID: 17074360 DOI: 10.1016/j.jinsphys.2006.09.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 09/06/2006] [Accepted: 09/11/2006] [Indexed: 05/12/2023]
Abstract
In insects, especially in mosquitoes that are adult blood feeders, midgut remodeling is an important event during metamorphosis. It involves two processes viz., programmed cell death (PCD) of larval cells, and proliferation and differentiation of imaginal cells to form pupal/adult midgut. These processes are regulated by 20-hydroxyecdysone (20E) and juvenile hormone (JH), but the signaling mechanisms, which trigger specific changes remain poorly understood. Here, we report stage- and cell-specific expression of ecydone receptor (EcR), ultraspiracle (USP), broad (Br), E75B and hormone receptor 3 (HR3) during midgut remodeling in Aedes aegypti. In Ae. aegypti both EcR and USP genes code for two isoforms each and the expression of mRNA for these isoforms showed both stage- and cell-specific regulation. In general, EcR-B and USP-A mRNAs were detected during larval stages in larval cells, and EcR-A and USP-B mRNAs were detected during pupal stages in imaginal cells. These data suggest that EcR-B/USP-A heterodimer is important for PCD of larval cells and EcR-A/USP-B heterodimer is important for formation of pupal/adult midgut. Broad Z1 mRNA was detected only in the larval cells suggesting its primary role in PCD. It is likely that E75B and HR3 are probably involved in both PCD and imaginal cell proliferation and differentiation as their mRNAs were expressed in the larval as well as in imaginal cells. Application of JH analog, methoprene, lowered or delayed the expression of all the genes studied. These data suggest that 20E plays a major role in midgut remodeling and coordinates this process through stage- and cell-specific expression of different isoforms of nuclear receptors and transcription factors in the target larval and imaginal cells.
Collapse
|
60
|
Parthasarathy R, Palli SR. Developmental and hormonal regulation of midgut remodeling in a lepidopteran insect, Heliothis virescens. Mech Dev 2007; 124:23-34. [PMID: 17107775 DOI: 10.1016/j.mod.2006.09.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 09/12/2006] [Accepted: 09/16/2006] [Indexed: 11/22/2022]
Abstract
Midgut tissue undergoes remodeling during metamorphosis in insects belonging to orders Lepidoptera and Diptera. We investigated the developmental and hormonal regulation of these remodeling events in lepidopteran insect, Heliothis virescens. In H. virescens, programmed cell death (PCD) of larval midgut cells as well as proliferation and differentiation of imaginal cells began at 108 h after ecdysis to the final larval instar (AEFL) and proceeded through the pupal stages. Expression patterns of pro- cell death factors (caspase-1 and ICE) and anti-cell death factor, Inhibitor of Apoptosis (IAP) were studied in midguts during last larval and pupal stages. IAP, Caspase-1 and ICE mRNAs showed peaks at 48 h AEFL, 96 h AEFL and in newly formed pupae, respectively. Immunohistochemical analysis substantiated high caspase-3 activity in midgut at 108 h AEFL. Application of methoprene, a juvenile hormone analog (JHA) blocked PCD by maintaining high levels of IAP, downregulating the expression of caspase-1, ICE and inhibiting an increase in caspase-3 protein levels in midgut tissue. Also, the differentiation of imaginal cells was impaired by methoprene treatment. These studies demonstrate that presence of JHA during final instar larvae affects both midgut remodeling and larval-pupal metamorphosis leading to larval/pupal deformities in lepidopteran insects, a mechanism that is different from that in mosquito, Ae. aegypti where JHA uncouples midgut remodeling from metamorphosis.
Collapse
|
61
|
Rao CNR, Sarode PR, Parthasarathy R, Rao KJ. X-ray spectroscopic studies of amorphous materials. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/13642818008245407] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
62
|
Arakali AV, McCloskeyt J, Parthasarathy R, Alderfer JL, Chheda∗∗ GB, Srikrishnan T. Study of Creatinine and its 5-Alkoxy Analogs: Structure and Conformational Studies in the Solid and Solution States by X-Ray Crystallography, NMR, UV and Mass Spectrometry. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/07328319708002567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
63
|
Srikrishnan T, Parthasarathy R, Pfleiderer W, De** NC, Chheda** GB. Cis-transIsomerization of the N-Formyl Amino Group in a Novel Modified Uracil Derivative: 6-Amino-3-methyl-5-(N-Formylamino)uracil. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/07328319708001345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
64
|
Wu Y, Parthasarathy R, Bai H, Palli SR. Mechanisms of midgut remodeling: juvenile hormone analog methoprene blocks midgut metamorphosis by modulating ecdysone action. Mech Dev 2006; 123:530-47. [PMID: 16829058 DOI: 10.1016/j.mod.2006.05.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2006] [Revised: 05/17/2006] [Accepted: 05/20/2006] [Indexed: 11/21/2022]
Abstract
In holometabolous insects such as mosquito, Aedes aegypti, midgut undergoes remodeling during metamorphosis. Insect metamorphosis is regulated by several hormones including juvenile hormone (JH) and 20-hydroxyecdysone (20E). The cellular and molecular events that occur during midgut remodeling were investigated by studying nuclear stained whole mounts and cross-sections of midguts and by monitoring the mRNA levels of genes involved in 20E action in methoprene-treated and untreated Ae. aegypti. We used JH analog, methoprene, to mimic JH action. In Ae. aegypti larvae, the programmed cell death (PCD) of larval midgut cells and the proliferation and differentiation of imaginal cells were initiated at about 36h after ecdysis to the 4th instar larval stage (AEFL) and were completed by 12h after ecdysis to the pupal stage (AEPS). In methoprene-treated larvae, the proliferation and differentiation of imaginal cells was initiated at 36h AEFL, but the PCD was initiated only after ecdysis to the pupal stage. However, the terminal events that occur for completion of PCD during pupal stage were blocked. As a result, the pupae developed from methoprene-treated larvae contained two midgut epithelial layers until they died during the pupal stage. Quantitative PCR analyses showed that methoprene affected midgut remodeling by modulating the expression of ecdysone receptor B, ultraspiracle A, broad complex, E93, ftz-f1, dronc and drice, the genes that are shown to play key roles in 20E action and PCD. Thus, JH analog, methoprene acts on Ae. aegypti by interfering with the expression of genes involved in 20E action resulting in a block in midgut remodeling and death during pupal stage.
Collapse
|
65
|
Parthasarathy R. A community-based perspective. Indian J Psychiatry 2005; 47:215-7. [PMID: 20711309 PMCID: PMC2921137 DOI: 10.4103/0019-5545.43055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
66
|
Parthasarathy R, Gopinathan KP. Comparative analysis of the development of the mandibular salivary glands and the labial silk glands in the mulberry silkworm, Bombyx mori. Gene Expr Patterns 2005; 5:323-39. [PMID: 15661638 DOI: 10.1016/j.modgep.2004.10.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2004] [Revised: 10/13/2004] [Accepted: 10/18/2004] [Indexed: 11/20/2022]
Abstract
The mulberry silkworm, Bombyx mori has a pair of salivary glands arising from the mandibular segment, in addition to the labial silk glands which are generally considered as modified salivary glands. Here we report the characterization of salivary glands and the comparative gene expression profiling of the silk and salivary glands. The two independent salivary glands made up by 330 cells, grow about 1000 fold during larval development. These individual glands extend up to the T(1) thoracic segment unlike silk glands with fused anterior ends and extending up to the caudal region. The salivary glands also undergo endomitosis resembling the silk glands. The B. mori homologue of the homeotic gene Deformed (BmDfd) was expressed in the mandibular and maxillary segments in stage 17 embryo and got localized to the centre of the mandibular segment at stage 18 to form the salivary gland placodes. The expression was also seen in the distal ends of the leg appendages after blastokinesis (stage 22). Only low variations in BmDfd expression ranging from 1.6 to 2.1 fold were apparent during embryonic development. BmDfd expression was observed in the salivary glands all through the larval instars but not in the silk glands. The transcription factor, Forkhead and the segment polarity gene, Wingless were expressed throughout the salivary glands, the latter confirming the absence of physiological compartmentation within these glands unlike the silk glands. The expression of Amylase and Fibrohexamerin was restricted to the salivary and silk glands, respectively and therefore, served as molecular markers for these tissues.
Collapse
|
67
|
Lee SC, Parthasarathy R, Botwin K, Kunneman D, Rowold E, Lange G, Klover J, Abegg A, Zobel J, Beck T, Miller T, Hood W, Monahan J, McKearn JP, Jansson R, Voliva CF. Biochemical and immunological properties of cytokines conjugated to dendritic polymers. Biomed Microdevices 2005; 6:191-202. [PMID: 15377828 DOI: 10.1023/b:bmmd.0000042048.18186.ff] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Here we describe a post-translational modification of SC-63032, a variant of the species restricted, multi-lineage hematopoeitic factor human interleukin-3 (hIL-3). We have made two new dendritic polymer (polyamidoamine or PAMAM dendrimers, generation 5)-SC-63032 bioconjugates. Using two distinct chemistries (one of which is novel to this work), we achieved site-specific conjugation with respect to the amino acid in the proteins ligated to the dendrimers. In both bioconjugates, conjugated cytokine maintains its ability to bind the hIL-3 alpha receptor subunit, but is significantly (about 10-fold) less potent in inducing hIL-3 dependent in vitro cell proliferation than is the free cytokine. In vivo data indicates that conjugation decreases the immunogenicity of the conjugated cytokine modestly. In the absence of pharmacokinetic or biodistribution effects associated with the bioconjugates that increase their potency in vivo (which can only be tested in a higher primate, due to the species restriction of hIL-3 and its derivatives), these immune mitigation effects may be too small to be therapeutically significant. Though unmodified PAMAM dendrimers fail to elicit an antibody response in mice, protein conjugation to dendrimers haptenizes them, and a dendrimer-specific antibody response is produced. In toto, the principal limitation of the dendrimer-cytokine bioconjugates herein is in their reduced receptor affinity and potency in vitro. Were the in vivo potency of the bioconjugates to parallel the in vitro potency of the conjugates reported here, it is likely that particular dendrimer bioconjugates could not justify their higher costs of goods relative to the parent SC-63032 molecule, though retention of SC-63032 biological activities in conjugates suggests that other cytokine-dendrimer bioconjugates may be bioactive. This is good news to the nanotechnology community, in as much as PAMAM dendrimers are among the monodisperse polymeric nanomaterials available, and these results show that they can be used successfully in conjugates to bioactive proteins.
Collapse
|
68
|
Rønnow HM, Parthasarathy R, Jensen J, Aeppli G, Rosenbaum TF, McMorrow DF. Quantum Phase Transition of a Magnet in a Spin Bath. Science 2005; 308:389-92. [PMID: 15831752 DOI: 10.1126/science.1108317] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The excitation spectrum of a model magnetic system, LiHoF4, was studied with the use of neutron spectroscopy as the system was tuned to its quantum critical point by an applied magnetic field. The electronic mode softening expected for a quantum phase transition was forestalled by hyperfine coupling to the nuclear spins. We found that interactions with the nuclear spin bath controlled the length scale over which the excitations could be entangled. This generic result places a limit on our ability to observe intrinsic electronic quantum criticality.
Collapse
|
69
|
Suess L, Liu Y, Parthasarathy R, Dunning FB. Rydberg electron transfer to C6H5NO2: lifetimes and characteristics of the product C6H5NO2- ions. J Chem Phys 2005; 122:124315. [PMID: 15836386 DOI: 10.1063/1.1869983] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The nature of electron binding in C6H5NO2- ions produced by Rydberg electron transfer in K(np)C6H5NO2 collisions is investigated through measurements of the number and the lifetimes of the product ions and their dependence on Rydberg atom velocity and principal quantum number n in the range 12 <or approximately n <or approximately 30. The data are interpreted by comparison to results obtained using well-known dipole-bound and valence-bound anions. At high n direct capture into valence-bound states with a lifetime of approximately 1.6 ms is observed. At low n the data suggest that, while direct capture into valence-bound states is still possible, the majority of the observed C6H5NO2- ions result from the onset of a second reaction channel that involves the formation of a dipole-bound "doorway" state that rapidly evolves into a state with predominantly valence-bound character. These findings are discussed in the light of earlier work on electron binding to C6H5NO2.
Collapse
|
70
|
Suess L, Liu Y, Parthasarathy R, Dunning FB. Dynamics of Rydberg electron transfer to CH3CN: velocity dependent studies. J Chem Phys 2004; 121:7162-8. [PMID: 15473783 DOI: 10.1063/1.1795651] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The dynamics of free-ion production through electron transfer in K(np)/CH3CN collisions are examined through measurements using velocity-selected Rydberg atoms. The data show that Rydberg electron transfer leads to the creation of two groups of dipole-bound CH3CN- ions, one long lived (tau>85 micros), the other short lived (tau<1 micros). The velocity dependences associated with the production of both groups of ions are similar, the ion formation rate decreasing markedly with decreasing Rydberg atom velocity, principally as a consequence of postattachment electrostatic interactions between the product ions. The results are in reasonable accord with the predictions of a Monte Carlo collision model that considers the effect of crossings between the diabatic potential curves for the covalent K(np)/CH3CN system and the K+/CH3CN- ion pair. This model also accounts for the relatively small reaction rate constants, approximately 0.5-1.0 x 1.0(-8) cm(3) s(-1), associated with the formation of long-lived CH3CN- ions. No velocity dependence in the lifetime of the CH3CN- ions is observed.
Collapse
|
71
|
Stagner J, Mokshagundam S, Wyler K, Samols E, Rilo H, Stagner M, Parthasarathy L, Parthasarathy R. Beta-Cell sparing in transplanted islets by vascular endothelial growth factor. Transplant Proc 2004; 36:1178-80. [PMID: 15194408 DOI: 10.1016/j.transproceed.2004.04.036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have reported that vascular endothelial growth factor (VEGF) promotes the revascularization of transplanted islets, thereby reducing the initial number required to prevent diabetes. The present study was undertaken to assess other mechanisms of beta-cell sparing by VEGF. For in vitro studies, islets were cultured for 14 days with versus without 20 ng/mL VEGF. Viability, necrosis, and apoptosis were examined by specific staining (Alcein AM, propidium iodide, and annexin/phosphatidylserine). The effects of VEGF on islets were also examined in a proteomic study. In vivo streptozotocin-treated diabetic Lewis rats received 1000 Lewis or Sprague-Dawley islets beneath the renal capsule. Oxygen levels at the transplant site were monitored by a Clark-type oxygen electrode. Fasting blood glucose served as an indicator of islet survival and function. VEGF enhanced oxygen levels at the transplant site. Syngeneic recipients were euglycemic for over 6 months, whereas control islets failed within 30 to 60 days. VEGF prevented allograft rejection for over 14 days, whereas controls were rejected within 6 to 7 days. Immunostaining suggested that VEGF inhibited the presentation of MHC II antigen and promoted islet survival by the inhibition of necrosis and apoptosis. Our proteomic study suggested VEGF preserved systems required for cellular preservation (heat shock proteins) and insulin secretion. VEGF promotes the preservation of isolated and transplanted islets by a variety of mechanisms, including enhanced oxygenation and inhibition of immune rejection, necrosis, and apoptosis. The provision of exogenous VEGF may be a useful adjunct to islet transplantation.
Collapse
|
72
|
Suess L, Liu Y, Parthasarathy R, Dunning FB. Dipole-bound negative ions: Collisional destruction and blackbody-radiation-induced photodetachment. J Chem Phys 2003. [DOI: 10.1063/1.1628215] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
|
73
|
Suess L, Parthasarathy R, Dunning FB. Rydberg electron transfer to CH3NO2: Lifetimes and characteristics of the product CH3NO2− ions. J Chem Phys 2003. [DOI: 10.1063/1.1615516] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
|
74
|
Matlock P, Viswanathan KS, Yang Y, Parthasarathy R. Neveu-Schwarz 5-brane and little string duality in thepp-wave limit. Int J Clin Exp Med 2003. [DOI: 10.1103/physrevd.68.086001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
75
|
Parthasarathy R, Suess L, Liu Y, Dunning FB. Formation of dipole-bound negative ions in Rydberg atom collisions: A signature. J Chem Phys 2003. [DOI: 10.1063/1.1595093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
|
76
|
Suess L, Parthasarathy R, Dunning FB. Free ion formation in K(np)/SF6 collisions at low-to-intermediate n: Velocity dependence of the number and lifetime of the product ions. J Chem Phys 2003. [DOI: 10.1063/1.1574804] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
|
77
|
Suess L, Parthasarathy R, Dunning F. Rydberg electron transfer to CS2: properties of the product CS2− ions. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00480-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
78
|
Suess L, Parthasarathy R, Dunning FB. Nondissociative low energy electron attachment to C2Cl4:C2Cl4− ion lifetime. J Chem Phys 2003. [DOI: 10.1063/1.1557454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
|
79
|
Suess L, Parthasarathy R, Dunning FB. Nondissociative low-energy electron attachment to SF6, C6F6, C10F8, and c-C7F14: Negative ion lifetimes. J Chem Phys 2002. [DOI: 10.1063/1.1522713] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
|
80
|
Ghosh S, Parthasarathy R, Rosenbaum TF, Aeppli G. Coherent spin oscillations in a disordered magnet. Science 2002; 296:2195-8. [PMID: 12077409 DOI: 10.1126/science.1070731] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Most materials freeze when cooled to sufficiently low temperature. We find that magnetic dipoles randomly distributed in a solid matrix condense into a spin liquid with spectral properties on cooling that are the diametric opposite of those for conventional glasses. Measurements of the nonlinear magnetic dynamics in the low-temperature liquid reveal the presence of coherent spin oscillations composed of hundreds of spins with lifetimes of up to 10 seconds. These excitations can be labeled by frequency and manipulated by the magnetic fields from a loop of wire and can permit the encoding of information at multiple frequencies simultaneously.
Collapse
|
81
|
Srikrishnan T, Fridey SM, Parthasarathy R. Conformation of 3'-nucleotides. Crystal structure of uncharged 3'-uridine monophosphate monohydrate and hydrogen bonding to the furanose ring oxygen. J Am Chem Soc 2002. [DOI: 10.1021/ja00508a006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
82
|
Row TNG, Parthasarathy R. Directional preferences of nonbonded atomic contacts with divalent sulfur in terms of its orbital orientations. 2. Sulfur.cntdot..cntdot..cntdot.sulfur interactions and nonspherical shape of sulfur in crystals. J Am Chem Soc 2002. [DOI: 10.1021/ja00392a047] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
83
|
Parthasarathy R, Paul B, Korytnyk W. X-ray and NMR studies on thiazolidines: crystal structure and conformational equilibriums of N-acetyl-2-(p-tolyl)thiazolidine-4-carboxylic acid ad related thiazolidine derivatives. J Am Chem Soc 2002. [DOI: 10.1021/ja00437a036] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
84
|
Desiraju GR, Parthasarathy R. The nature of halogen.cntdot..cntdot..cntdot.halogen interactions: are short halogen contacts due to specific attractive forces or due to close packing of nonspherical atoms? J Am Chem Soc 2002. [DOI: 10.1021/ja00205a027] [Citation(s) in RCA: 637] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
85
|
Rosenfield RE, Parthasarathy R, Dunitz JD. Directional preferences of nonbonded atomic contacts with divalent sulfur. 1. Electrophiles and nucleophiles. J Am Chem Soc 2002. [DOI: 10.1021/ja00456a072] [Citation(s) in RCA: 420] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
86
|
Ohrt JM, Srikrishnan T, Parthasarathy R, Dutta SP, Chheda GB. Unequivocal structural assignments of N7- and N9-acyladenines. J Am Chem Soc 2002. [DOI: 10.1021/ja00484a066] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
87
|
Ohrt JM, Parthasarathy R, Chheda GB. Crystal and molecular structure of a tricyclic purine intermediate. 3-Methyl-3H-imidazo[2,1-i]purine-8(7H)-one. J Am Chem Soc 2002. [DOI: 10.1021/ja00725a037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
88
|
Nash CP, Olmstead MM, Weiss-Lopez B, Musker WK, Ramasubbu N, Parthasarathy R. Structures and Raman spectra of two crystalline modifications of dithiodiglycolic acid. J Am Chem Soc 2002. [DOI: 10.1021/ja00310a083] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
89
|
Bobek M, Glowka M, Parthasarathy R. Synthesis and the crystal structure of 4-(2-deoxy-.beta.-D-erythro-pentofuranosyl)-6-methyl-1,2,4-triazin-3-(4H)-one 1-oxide, a structural analog of thymidine. J Org Chem 2002. [DOI: 10.1021/jo00345a002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
90
|
Ramasubbu N, Parthasarathy R, Murray-Rust P. Angular preferences of intermolecular forces around halogen centers: preferred directions of approach of electrophiles and nucleophiles around carbon-halogen bond. J Am Chem Soc 2002. [DOI: 10.1021/ja00275a012] [Citation(s) in RCA: 427] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
91
|
Parthasarathy R, Rao KJ, Rao CNR. Dielectric and electron spin resonance spectroscopic studies of glassy crystalline states of organic compounds. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j150645a012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
92
|
Koul D, Parthasarathy R, Shen R, Davies MA, Jasser SA, Chintala SK, Rao JS, Sun Y, Benvenisite EN, Liu TJ, Yung WK. Suppression of matrix metalloproteinase-2 gene expression and invasion in human glioma cells by MMAC/PTEN. Oncogene 2001; 20:6669-78. [PMID: 11709701 DOI: 10.1038/sj.onc.1204799] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2000] [Revised: 06/07/2001] [Accepted: 06/11/2001] [Indexed: 01/21/2023]
Abstract
Human gliomas are highly invasive, and remain to be a major obstacle for any effective therapeutic remedy. Among many other factors, gliomas express elevated levels of matrix metalloproteinases (MMPs), which have been implicated to play an important role in tumor invasion as well as neovascularization. The tumor suppressor gene mutated in multiple advanced cancers/phosphatase and tensin homologue (MMAC/PTEN) has been shown to inhibit cell migration, spreading, and focal adhesion. In this study, we determined whether MMAC/PTEN inhibits tumor invasion by modulating MMP-2 activity. Our results showed that reintroduction of the MMAC/PTEN gene into human glioma U251 and U87 cells modified their phenotype and growth characteristics. The ability of MMAC/PTEN to induce anoikis in U251 cells was accompanied by a significant inhibition of in vitro invasion (70%). Expression of MMAC/PTEN in U251 and U87 cells inhibited MMP-2 enzymatic activity as determined by zymography. Furthermore, MMAC/PTEN expression strongly decreased MMP-2 mRNA levels, which correlated well with the inhibition of invasion capacity in these cells. Concomitant with MMP-2 expression and activity, MMP-2 promoter activity was also reduced in MMAC/PTEN expressing cells. Our observations suggest that MMAC/PTEN inhibits tumor cell invasion in part by regulating MMP-2 gene transcription and thereby its enzymatic activity. Further characterization of this regulation will facilitate the development of MMAC/PTEN based gene therapy for gliomas.
Collapse
|
93
|
Parthasarathy R, Suess L, Hill SB, Dunning FB. Low-energy dissociative electron attachment to BrCN and CBrCl3: Temperature dependences and reaction dynamics. J Chem Phys 2001. [DOI: 10.1063/1.1364686] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
94
|
|
95
|
|
96
|
Abstract
Based upon experimental results on certain visual spatial discrimination tasks, we have developed a formalism for a non-Euclidian perceptual space. In this formalism, the transformation from real to perceptual space is given by a generalized covariant tensor. The concept of parallel transport of vectors in a curved space is used to prove that closed loops in real space imply closed loops with the same orientation in the perceptual space also.
Collapse
|
97
|
Voci SL, Gottlieb RH, Fultz PJ, Mehta A, Parthasarathy R, Rubens DJ, Strang JG. Delayed computed tomographic characterization of renal masses: preliminary experience. ABDOMINAL IMAGING 2000; 25:317-21. [PMID: 10823459 DOI: 10.1007/s002610000009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND To evaluate the performance of delayed contrast enhanced computed tomography (DCT) in characterizing renal masses. METHODS Twenty-four patients with suspected renal masses or indeterminate renal masses on previous imaging studies were prospectively evaluated with preintravenous contrast imaging, conventional contrast-enhanced computed tomography (imaging initiated 2 min after intravenous contrast injection), and DCT (imaging initiated 13 min after injection of intravenous contrast). Only lesions larger than 1.0 cm were evaluated, with scanning parameters kept constant across the three scans. RESULTS All pathologically confirmed renal cell carcinomas (n = 6) were detected on DCT using a threshold attenuation decrease of 10 Hounsfield units (HU). A significant decrease (p = 0.031) in attenuation occurred in renal cell carcinomas (mean = 29.6 +/- 23.6 HU) compared with the attenuation change (mean decrease = 1.1 +/- 7.1 HU), which occurred in non-neoplastic renal cysts (n = 34). Non-neoplastic renal cysts were correctly classified by DCT 32 of 34 times (94%). CONCLUSIONS In this study, DCT distinguished renal cell carcinomas from non-neoplastic cysts in a vast majority of cases and may aid in characterizing incidentally discovered renal lesions on postcontrast CT.
Collapse
|
98
|
Parthasarathy R, Kayasth S, Verma R, Mathur PK, Anupama P, Anilkumar S. J Radioanal Nucl Chem 2000; 246:239-242. [DOI: 10.1023/a:1006796324755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
99
|
Finch CD, Parthasarathy R, Hill SB, Dunning FB. Nondissociative low-energy electron attachment to c-C7F14 and C6F6: Intermediate lifetimes. J Chem Phys 1999. [DOI: 10.1063/1.480054] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
100
|
Parthasarathy R, Cote GJ, Gagel RF. Hammerhead ribozyme-mediated inactivation of mutant RET in medullary thyroid carcinoma. Cancer Res 1999; 59:3911-4. [PMID: 10463581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Activating mutations of the RET proto-oncogene cause hereditary medullary thyroid carcinoma. To examine whether selective inactivation of mutant RET could prevent transformation, a hammerhead ribozyme was designed to cleave RET mRNA containing a transforming mutation of codon 634 TGC --> TAC (Cys634Tyr). In vitro RNA cleavage assay demonstrated that the ribozyme selectively cleaved RET RNA with a Cys634Tyr but not Cys634Arg or the normal sequence. Expression of ribozyme in NIH/3T3 cells prevented RET-mediated colony formation in soft agar. This inhibition required catalytically active ribozyme and was specific for the TAC mutation. Therefore, ribozymes designed to selectively target mutant RET RNA may provide an effective therapeutic in the treatment of this syndrome.
Collapse
|