51
|
Choudhury S, Gunjal S, Kumari N, Diwate K, Mohite K, Bhattacharjee A. Facile synthesis of SnO2 thin film by spray pyrolysis technique, investigation of the structural, optical, electrical properties. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.matpr.2016.04.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
52
|
Gurung A, Ali M, Bhattacharjee A, Al-Anazi K, Farah M, Al-Hemaid F, Abou-Tarboush F, Lee J, Kim S, Al-Anazi F. Target fishing of glycopentalone using integrated inverse docking and reverse pharmacophore mapping approach. GENETICS AND MOLECULAR RESEARCH 2016; 15:gmr8544. [DOI: 10.4238/gmr.15038544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
53
|
Squire J, Bhattacharjee A. Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:053101. [PMID: 26651796 DOI: 10.1103/physreve.92.053101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Indexed: 06/05/2023]
Abstract
This article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to magnetic fluctuations can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of α effects in the stratified regions of disks gives the puzzling result that there is no strong prediction for a sign of α, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.
Collapse
|
54
|
Stanier A, Daughton W, Chacón L, Karimabadi H, Ng J, Huang YM, Hakim A, Bhattacharjee A. Role of Ion Kinetic Physics in the Interaction of Magnetic Flux Ropes. PHYSICAL REVIEW LETTERS 2015; 115:175004. [PMID: 26551121 DOI: 10.1103/physrevlett.115.175004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 06/05/2023]
Abstract
To explain many natural magnetized plasma phenomena, it is crucial to understand how rates of collisionless magnetic reconnection scale in large magnetohydrodynamic (MHD) scale systems. Simulations of isolated current sheets conclude such rates are independent of system size and can be reproduced by the Hall-MHD model, but neglect sheet formation and coupling to MHD scales. Here, it is shown for the problem of flux-rope merging, which includes this formation and coupling, that the Hall-MHD model fails to reproduce the kinetic results. The minimum sufficient model must retain ion kinetic effects, which set the ion diffusion region geometry and give time-averaged rates that reduce significantly with system size, leading to different global evolution in large systems.
Collapse
|
55
|
Squire J, Bhattacharjee A. Generation of Large-Scale Magnetic Fields by Small-Scale Dynamo in Shear Flows. PHYSICAL REVIEW LETTERS 2015; 115:175003. [PMID: 26551120 DOI: 10.1103/physrevlett.115.175003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Indexed: 06/05/2023]
Abstract
We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the "shear-current" effect. Given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic nature of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.
Collapse
|
56
|
Kane S, Patil VM, Joshi A, Noronha V, Muddu V, Dhumal S, Juvekar S, Arya S, D'Cruz A, Bhattacharjee A, Prabhash K. Neoadjuvant Chemotherapy in Technically Unresectable Oral Cancers: Does Human Papillomavirus Make a Difference? Clin Oncol (R Coll Radiol) 2015; 27:751-3. [PMID: 26412438 DOI: 10.1016/j.clon.2015.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/14/2015] [Accepted: 09/08/2015] [Indexed: 11/24/2022]
|
57
|
Hasanain M, Bhattacharjee A, Pandey P, Ashraf R, Singh N, Sharma S, Vishwakarma AL, Datta D, Mitra K, Sarkar J. α-Solanine induces ROS-mediated autophagy through activation of endoplasmic reticulum stress and inhibition of Akt/mTOR pathway. Cell Death Dis 2015; 6:e1860. [PMID: 26313911 PMCID: PMC4558510 DOI: 10.1038/cddis.2015.219] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 06/09/2015] [Accepted: 06/19/2015] [Indexed: 12/21/2022]
Abstract
α-Solanine is a glycoalkaloid found in species of the nightshade family including potato. It was primarily reported to have toxic effects in humans. However, there is a growing body of literature demonstrating in vitro and in vivo anticancer activity of α-solanine. Most of these studies have shown activation of apoptosis as the underlying mechanism in antitumor activity of α-solanine. In this study, we report α-solanine as a potential inducer of autophagy, which may act synergistically or in parallel with apoptosis to exert its cytotoxic effect. Induction of autophagy was demonstrated by several assays including electron microscopy, immunoblotting of autophagy markers and immunofluorescence for LC3 (microtubule-associated protein 1 (MAP1) light chain-3) puncta. α-Solanine-induced autophagic flux was demonstrated by additionally enhanced – turnover of LC3-II and – accumulation of LC3-specific puncta after co-incubation of cells with either of the autophagolysosome inhibitors – chloroquine and – bafilomycin A1. We also demonstrated α-solanine-induced oxidative damage in regulating autophagy where pre-incubation of cells with reactive oxygen species (ROS) scavenger resulted in suppression of CM-H2DCFDA (5 (and 6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate acetyl ester) fluorescence as well as decrease in LC3-II turnover. α-Solanine treatment caused an increase in the expression of endoplasmic reticulum (ER) stress proteins (BiP, activating transcription factor 6 (ATF6), X-box-binding protein 1, PERK, inositol-requiring transmembrane kinase/endonuclease 1, ATF4 and CCAAT-enhancer-binding protein (C/EBP)-homologous protein) suggesting activation of unfolded protein response pathway. Moreover, we found downregulation of phosphorylated Akt (Thr308 and Ser473), mammalian target of rapamycin (mTOR; Ser2448 and Ser2481) and 4E-BP1 (Thr37/46) by α-solanine implying suppression of the Akt/mTOR pathway. Collectively, our results signify that α-solanine induces autophagy to exert anti-proliferative activity by triggering ER stress and inhibiting Akt/mTOR signaling pathway.
Collapse
|
58
|
Ghosh P, Singha Roy S, Basu A, Bhattacharjee A, Bhattacharya S. Sensitization of cisplatin therapy by a naphthalimide based organoselenium compound through modulation of antioxidant enzymes and p53 mediated apoptosis. Free Radic Res 2015; 49:453-71. [PMID: 25730340 DOI: 10.3109/10715762.2015.1012079] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The widely used anti-cancer drug cisplatin imparts various toxic manifestations in the host, with nephrotoxicity being the most severe one. The trace element selenium shows antioxidant activity in both human and animals. The present study was designed to assess the chemoprotecting and chemoenhancing efficacy of a naphthalimide based organoselenium compound 2-(5-selenocyanato-pentyl)-benzo[de]isoquinoline 1,3-dione during cisplatin chemotherapy in mice bearing Ehrlich ascites carcinoma cells. Cisplatin (5 mg/kg b.w.) was administered intraperitoneally and the organoselenium compound (3 mg/kg b.w.) was given by oral gavage in concomitant and pretreatment schedule. The effects of the test compound was evaluated by assaying biochemical, hematological, histological, genotoxicity parameters and by investigating induction of apoptosis in tumor cells, and calculating tumor growth response in the host. The organoselenium compound significantly prevented cisplatin induced generation of reactive oxygen species (ROS), reactive nitrogen species, and onset of lipid peroxidation in the kidney tissue of the experimental mice. In addition, the test compound was also substantially restored cisplatin induced depleted activities of the renal antioxidant enzymes and reduced glutathione level; prevented the serum blood urea nitrogen level, creatinine level, chromosomal aberration, DNA damage, histological alterations of kidney, and normalized the hematological profile of the tumor bearing mice. Furthermore, the organoselenium compound alone or during combination therapy induced apoptosis in tumor cells through mitochondria mediated and DNA damage mediated pathway and ultimately increased the life span of the tumor bearing host. Hence, the results showed that the test compound not only reduced the toxicity of cisplatin but also enhanced its anti-tumor efficacy.
Collapse
|
59
|
Squire J, Bhattacharjee A. Statistical simulation of the magnetorotational dynamo. PHYSICAL REVIEW LETTERS 2015; 114:085002. [PMID: 25768767 DOI: 10.1103/physrevlett.114.085002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Indexed: 06/04/2023]
Abstract
Turbulence and dynamo induced by the magnetorotational instability (MRI) are analyzed using quasilinear statistical simulation methods. It is found that homogenous turbulence is unstable to a large-scale dynamo instability, which saturates to an inhomogenous equilibrium with a strong dependence on the magnetic Prandtl number (Pm). Despite its enormously reduced nonlinearity, the dependence of the angular momentum transport on Pm in the quasilinear model is qualitatively similar to that of nonlinear MRI turbulence. This demonstrates the importance of the large-scale dynamo and suggests how dramatically simplified models may be used to gain insight into the astrophysically relevant regimes of very low or high Pm.
Collapse
|
60
|
Noronha V, Patil V, Karpe A, Joshi A, Muddu V, Bhattacharjee A, Dhumal S, Prabhash K. Efficacy of second-line erlotinib in patients postprogression of first-line chemotherapy in head and neck cancers. Indian J Cancer 2015; 52:629-31. [DOI: 10.4103/0019-509x.178374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
61
|
Ajij M, Paul D, Bhattacharjee A. Carriage of quinolone resistance in faecal coliforms among healthy individuals: A study from northeast India. Indian J Med Microbiol 2015; 33:190-1. [DOI: 10.4103/0255-0857.148441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
62
|
Gurung A, Mylliemngap B, Bhattacharjee A, Ali M, Al-Hemaid F. Interactome analysis and design of inhibitors against selected protein targets of Ser/Thr protein kinase (STPK) signaling pathways in Mycobacterium tuberculosis H37Rv. GENETICS AND MOLECULAR RESEARCH 2015; 14:10390-403. [DOI: 10.4238/2015.september.1.6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
63
|
Bhattacharyya T, Bhattacharjee A. Competing risk: An illustration with aspiration pneumonia in head and neck cancer patients undergoing radical radiotherapy: A biostatistician's perspective. Indian J Cancer 2014; 51:406-9. [PMID: 26842137 DOI: 10.4103/0019-509x.175322] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Interest in survival analysis is to look and capture the information about the occurrence of events, i.e., death. In human life different types of events may happen at the same time. Sometimes, few events completely interrupt or make subtle changes on the occurrence of an event of interest. The method to capture information about the specific event of interest along with other events is known as competing risk modeling. This paper is dedicated to explore the application of competing risk model in oncology practice. It is aimed in near future that more and more survival analysis will be performed through application of competing risk modeling instead of traditional survival analysis to generate robust statistical inference.
Collapse
|
64
|
Fiksel G, Fox W, Bhattacharjee A, Barnak DH, Chang PY, Germaschewski K, Hu SX, Nilson PM. Magnetic reconnection between colliding magnetized laser-produced plasma plumes. PHYSICAL REVIEW LETTERS 2014; 113:105003. [PMID: 25238366 DOI: 10.1103/physrevlett.113.105003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Indexed: 06/03/2023]
Abstract
Observations of magnetic reconnection between colliding plumes of magnetized laser-produced plasma are presented. Two counterpropagating plasma flows are created by irradiating oppositely placed plastic (CH) targets with 1.8-kJ, 2-ns laser beams on the Omega EP Laser System. The interaction region between the plumes is prefilled with a low-density background plasma and magnetized by an externally applied magnetic field, imposed perpendicular to the plasma flow, and initialized with an X-type null point geometry with B=0 at the midplane and B=8 T at the targets. The counterflowing plumes sweep up and compress the background plasma and the magnetic field into a pair of magnetized ribbons, which collide, stagnate, and reconnect at the midplane, allowing the first detailed observations of a stretched current sheet in laser-driven reconnection experiments. The dynamics of current sheet formation are in good agreement with first-principles particle-in-cell simulations that model the experiments.
Collapse
|
65
|
Crainic V, de Grosbois J, Lung T, Bhattacharjee A, Tremblay L. Limb-target regulation processes: Further evidence for a sweet spot. J Vis 2014. [DOI: 10.1167/14.10.415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
66
|
Manzone D, Bhattacharjee A, de Grosbois J, Manson G, Loria T, Lung T, Tremblay L. Another look at binocular vision: Contribution to online control processes. J Vis 2014. [DOI: 10.1167/14.10.419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
67
|
Squire J, Bhattacharjee A. Nonmodal growth of the magnetorotational instability. PHYSICAL REVIEW LETTERS 2014; 113:025006. [PMID: 25062200 DOI: 10.1103/physrevlett.113.025006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Indexed: 06/03/2023]
Abstract
We analyze the linear growth of the magnetorotational instability (MRI) in the short-time limit using nonmodal methods. Our findings are quite different from standard results, illustrating that shearing wave energy can grow at the maximum MRI rate -dΩ/dlnr for any choice of azimuthal and vertical wavelengths. In addition, by comparing the growth of shearing waves with static structures, we show that over short time scales shearing waves will always be dynamically more important than static structures in the ideal limit. By demonstrating that fast linear growth is possible at all wavelengths, these results suggest that nonmodal linear physics could play a fundamental role in MRI turbulence.
Collapse
|
68
|
Yadav P, Chatterjee A, Bhattacharjee A. Identification of deleterious nsSNPs in α, μ, π and θ class of GST family and their influence on protein structure. GENOMICS DATA 2014; 2:66-72. [PMID: 26484073 PMCID: PMC4535831 DOI: 10.1016/j.gdata.2014.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/21/2014] [Accepted: 03/31/2014] [Indexed: 02/08/2023]
Abstract
GST family genes have a critical role in xenobiotic metabolism and drug resistance. Among the GST family the GST-μ, GST-π, GST-α and GST-θ are the most abundant classes and have a major role in the carcinogen detoxification process. Nevertheless the activity of these enzymes may differ due to polymorphisms which ultimately results in interindividual susceptibility to cancer development. In this work, we have analyzed the potentially deleterious nsSNPs that can alter the function of these genes. As a result among the nsSNPs, 101 (42.61%) were found to be deleterious by a sequence homology-based tool, 67 (28.27%) by a structure homology based tool and a total of 59 (24.89%) by both. We propose a modeled structure of the five highly deleterious mutant proteins. Our results will provide useful information in selecting target SNPs that are likely to have an impact on GST activity and contribute to an individual's susceptibility to the disease.
Collapse
|
69
|
Ebrahimi F, Bhattacharjee A. Helicity-flux-driven α effect in laboratory and astrophysical plasmas. PHYSICAL REVIEW LETTERS 2014; 112:125003. [PMID: 24724656 DOI: 10.1103/physrevlett.112.125003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Indexed: 06/03/2023]
Abstract
The constraint imposed by magnetic helicity conservation on the α effect is considered for both magnetically and flow dominated self-organizing plasmas. Direct numerical simulations are presented for a dominant contribution to the α effect, which can be cast in the functional form of a total divergence of an averaged helicity flux, called the helicity-flux-driven α (Hα) effect. Direct numerical simulations of the Hα effect are presented for two examples-the magnetically dominated toroidal plasma unstable to tearing modes, and the flow-dominated accretion disk.
Collapse
|
70
|
Joglekar AS, Thomas AGR, Fox W, Bhattacharjee A. Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law. PHYSICAL REVIEW LETTERS 2014; 112:105004. [PMID: 24679302 DOI: 10.1103/physrevlett.112.105004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Indexed: 06/03/2023]
Abstract
In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfvènic flows. We find that this mechanism is only relevant in a high β plasma. However, the Hall parameter ωcτei can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system.
Collapse
|
71
|
Fox W, Fiksel G, Bhattacharjee A, Chang PY, Germaschewski K, Hu SX, Nilson PM. Filamentation instability of counterstreaming laser-driven plasmas. PHYSICAL REVIEW LETTERS 2013; 111:225002. [PMID: 24329452 DOI: 10.1103/physrevlett.111.225002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Indexed: 06/03/2023]
Abstract
Filamentation due to the growth of a Weibel-type instability was observed in the interaction of a pair of counterstreaming, ablatively driven plasma flows, in a supersonic, collisionless regime relevant to astrophysical collisionless shocks. The flows were created by irradiating a pair of opposing plastic (CH) foils with 1.8 kJ, 2-ns laser pulses on the OMEGA EP Laser System. Ultrafast laser-driven proton radiography was used to image the Weibel-generated electromagnetic fields. The experimental observations are in good agreement with the analytical theory of the Weibel instability and with particle-in-cell simulations.
Collapse
|
72
|
Upadhyay S, Mishra S, Sen MR, Banerjee T, Bhattacharjee A. Co-existence of Pseudomonas-derived cephalosporinase among plasmid encoded CMY-2 harbouring isolates of Pseudomonas aeruginosa in north India. Indian J Med Microbiol 2013; 31:257-60. [DOI: 10.4103/0255-0857.115629] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
73
|
Meri T, Amdahl H, Lehtinen MJ, Hyvärinen S, McDowell JV, Bhattacharjee A, Meri S, Marconi R, Goldman A, Jokiranta TS. Microbes bind complement inhibitor factor H via a common site. PLoS Pathog 2013; 9:e1003308. [PMID: 23637600 PMCID: PMC3630169 DOI: 10.1371/journal.ppat.1003308] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 03/02/2013] [Indexed: 11/18/2022] Open
Abstract
To cause infections microbes need to evade host defense systems, one of these being the evolutionarily old and important arm of innate immunity, the alternative pathway of complement. It can attack all kinds of targets and is tightly controlled in plasma and on host cells by plasma complement regulator factor H (FH). FH binds simultaneously to host cell surface structures such as heparin or glycosaminoglycans via domain 20 and to the main complement opsonin C3b via domain 19. Many pathogenic microbes protect themselves from complement by recruiting host FH. We analyzed how and why different microbes bind FH via domains 19–20 (FH19-20). We used a selection of FH19-20 point mutants to reveal the binding sites of several microbial proteins and whole microbes (Haemophilus influenzae, Bordetella pertussis, Pseudomonas aeruginosa, Streptococcus pneumonia, Candida albicans, Borrelia burgdorferi, and Borrelia hermsii). We show that all studied microbes use the same binding region located on one side of domain 20. Binding of FH to the microbial proteins was inhibited with heparin showing that the common microbial binding site overlaps with the heparin site needed for efficient binding of FH to host cells. Surprisingly, the microbial proteins enhanced binding of FH19-20 to C3b and down-regulation of complement activation. We show that this is caused by formation of a tripartite complex between the microbial protein, FH, and C3b. In this study we reveal that seven microbes representing different phyla utilize a common binding site on the domain 20 of FH for complement evasion. Binding via this site not only mimics the glycosaminoglycans of the host cells, but also enhances function of FH on the microbial surfaces via the novel mechanism of tripartite complex formation. This is a unique example of convergent evolution resulting in enhanced immune evasion of important pathogens via utilization of a “superevasion site.” Complement is an important arm of innate immunity. Activation of this plasma protein cascade leads to opsonization of targets for phagocytosis, direct lysis of Gram-negative bacteria, and enhancement of the inflammatory and acquired immune responses. No specific signal is needed for activation of the alternative pathway of complement, leading to its activation on all unprotected surfaces. Pathogenic microbes need to evade this pathway, and several species are known to recruit host complement inhibitor factor H (FH) to prevent the activation. FH is important for protection of host cells, too, as defects in FH lead to a severe autoreactive disease, atypical hemolytic uremic syndrome. We have now identified at the molecular level a common mechanism by which seven different microbes, Haemophilus influenzae, Bordetella pertussis, Pseudomonas aeruginosa, Streptococcus pneumoniae, Candida albicans, Borrelia burgdorferi and B. hermsii, recruit FH. All microbes bind FH via a common site on domain 20, which facilitates formation of a tripartite complex between the microbial protein, the main complement opsonin C3b, and FH. We show that, by utilizing the common microbial binding site on FH20, microbes can inhibit complement more efficiently. This detailed knowledge on mechanism of complement evasion can be used in developing novel antimicrobial chemotherapy.
Collapse
|
74
|
Huang YM, Bhattacharjee A. Distribution of plasmoids in high-Lundquist-number magnetic reconnection. PHYSICAL REVIEW LETTERS 2012; 109:265002. [PMID: 23368572 DOI: 10.1103/physrevlett.109.265002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Indexed: 06/01/2023]
Abstract
The distribution function f(ψ) of magnetic flux ψ in plasmoids formed in high-Lundquist-number current sheets is studied by means of an analytic phenomenological model and direct numerical simulations. The distribution function is shown to follow a power law f(ψ)∼ψ(-1), which differs from other recent theoretical predictions. Physical explanations are given for the discrepant predictions of other theoretical models.
Collapse
|
75
|
Kajander T, Lehtinen M, Hyvärinen S, Bhattacharjee A, Meri T, Kolodziejczyk R, Meri S, Jokiranta S, Goldman A. Factor H ligand complexes – structural studies on complement regulation and disease. Acta Crystallogr A 2012. [DOI: 10.1107/s0108767312099357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|