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Shaw SG, Hassan-Ibrahim M, Soni S. Are we missing pharyngeal and rectal infections in women by not testing those who report oral and anal sex? Sex Transm Infect 2013; 89:397. [PMID: 23858500 DOI: 10.1136/sextrans-2013-051159] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Soni S, Corradini E, Van Der Nagel R, Boulaksil M, Heck AJR, Scholten AJR, Vos MA, Van Veen TAB. Anchored cAMP signalling in progression from hypertrophy to heart failure in a rat model of pressure overload. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht310.p5715] [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: 11/15/2022] Open
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Mohapatra NP, Soni S, Rajaram MVS, Strandberg KL, Gunn JS. Type A Francisella tularensis acid phosphatases contribute to pathogenesis. PLoS One 2013; 8:e56834. [PMID: 23457625 PMCID: PMC3574111 DOI: 10.1371/journal.pone.0056834] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 01/15/2013] [Indexed: 12/02/2022] Open
Abstract
Different Francisella spp. produce five or six predicted acid phosphatases (AcpA, AcpB, AcpC, AcpD, HapA and HapB). The genes encoding the histidine acid phosphatases (hapA, hapB) and acpD of F. tularensis subsp. Schu S4 strain are truncated or disrupted. However, deletion of HapA (FTT1064) in F. tularensis Schu S4 resulted in a 33% reduction in acid phosphatase activity and loss of the four functional acid phosphatases in F. tularensis Schu S4 (ΔABCH) resulted in a>99% reduction in acid phosphatase activity compared to the wild type strain. All single, double and triple mutants tested, demonstrated a moderate decrease in mouse virulence and survival and growth within human and murine phagocytes, whereas the ΔABCH mutant showed >3.5-fold decrease in intramacrophage survival and 100% attenuation of virulence in mouse. While the Schu S4 ΔABCH strain was attenuated in the mouse model, it showed only limited protection against wild type challenge. F. tularensis Schu S4 failed to stimulate reactive oxygen species production in phagocytes, whereas infection by the ΔABCH strain stimulated 5- and 56-fold increase in reactive oxygen species production in neutrophils and human monocyte-derived macrophages, respectively. The ΔABCH mutant but not the wild type strain strongly co-localized with p47phox and replicated in macrophages isolated from p47phox knockout mice. Thus, F. tularensis Schu S4 acid phosphatases, including the truncated HapA, play a major role in intramacrophage survival and virulence of this human pathogen.
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Soni S, Maitre S, Thomas S, Koertzen M. Automatic referral of patients after thoracic surgery to the pain team. Anaesthesia 2013. [DOI: 10.1111/anae.12143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Soni S, Rath G, Prasad CP, Salhan S, Saxena S, Jain AK. Apoptosis and Bcl-2 protein expression in human placenta over the course of normal pregnancy. Anat Histol Embryol 2012; 39:426-31. [PMID: 20608924 DOI: 10.1111/j.1439-0264.2010.01012.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Apoptosis plays a central role in organ development, homeostasis and immune defence in multicellular organisms and is strictly controlled in part by members of Bcl-2 family. The Bcl-2 is a pro-survival molecule identified through its involvement in B-cell lymphomas. The aim of the study was to evaluate the incidence of apoptosis in the human placenta at different stages of pregnancy and to correlate it further with Bcl-2 expression. A total of 96 placental samples from first trimester, mid-trimester and uncomplicated term pregnancies were collected (n = 32 + 32 + 32). M30 cyto death monoclonal antibody was used to identify apoptotic cells. The apoptosis index of first trimester placentae was 2.33 ± 1.70, mid- trimester was 1.77 ± 1.36 and term placenta was 1.15 ± 0.21. Bcl-2 protein was found immunolocalized in the cytoplasm of syncytiotrophoblast. Apoptosis index was significantly reduced in term cases as compared with first trimester (P < 0.002) and mid-trimester placentae (P = 0.01). On the contrary, Bcl-2 expression was significantly higher at term cases than in first trimester (P < 0.0001) and mid-trimester cases (P < 0.001). The present study divulges the importance of apoptosis in permitting normal physiological turnover of villous trophoblast and also exhibits the contribution of bcl-2 in maintaining syncytial integrity throughout normal pregnancy.
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Ackah F, Barrett A, Woodroffe T, Soni S. P157 Re-audit reflections: management of sexual assault attendances to GUM: Abstract P157 Table 1. Br J Vener Dis 2012. [DOI: 10.1136/sextrans-2012-050601c.157] [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]
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Simon S, Hassan-Ibrahim M, Soni S. P64 High rates of rectal Chlamydia trachomatisin women reporting anal sex in the GUM clinic: Abstract P64 Table 1. Br J Vener Dis 2012. [DOI: 10.1136/sextrans-2012-050601c.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Soni S, Dosekun O, Williams H, Fox J. Preventing onward HIV transmission in routine HIV care: low levels of evaluation of risk behaviour in HIV-infected patients. Br J Vener Dis 2011; 87:365. [DOI: 10.1136/sti.2010.049064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Rath G, Soni S, Prasad CP, Salhan S, Jain AK, Saxena S. Bcl-2 and p53 expressions in Indian women with complete hydatidiform mole. Singapore Med J 2011; 52:502-507. [PMID: 21808961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Hydatidiform moles have a high incidence rate in Asian countries like India. The molecular pathway leading to the pathogenesis and progression of hydatidiform moles is not yet understood. This study aimed to investigate the biological significance of Bcl-2 and p53 in complete hydatidiform moles (CHMs) as well as their influence on disease progression in the Indian population. METHODS Archival tissues from 35 patients with CHMs and 35 age-matched controls were examined for Bcl-2 and p53 expressions by immunohistochemistry. RESULTS Bcl-2 was found to be immunolocalised in the cytoplasm of the syncytiotrophoblast, whereas p53 was observed in both the nucleus and cytoplasm of the syncytiotrophoblast and cytotrophoblasts. In CHMs, Bcl-2 was detected in 23 percent of patients and p53 nuclear expression, in 66 percent. A significant decrease in Bcl-2 expression was observed in CHMs (p-value is 0.015), and the down-regulation of Bcl-2 significantly correlated with higher nuclear expression of p53 (p-value is 0.002), indicating an inverse association between the two proteins (p-value is 0.0001). However, no correlation was found between the clinical progress of patients with CHMs and p53 and those with Bcl-2 protein expression. CONCLUSION The current study demonstrated the significance of Bcl-2 and p53 in the pathogenesis of CHMs but did not reveal any association with disease progression.
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Maisel AS, Katz N, Hillege HL, Shaw A, Zanco P, Bellomo R, Anand I, Anker SD, Aspromonte N, Bagshaw SM, Berl T, Bobek I, Cruz DN, Daliento L, Davenport A, Haapio M, House AA, Mankad S, McCullough P, Mebazaa A, Palazzuoli A, Ponikowski P, Ronco F, Sheinfeld G, Soni S, Vescovo G, Zamperetti N, Ronco C. Biomarkers in kidney and heart disease. Nephrol Dial Transplant 2011; 26:62-74. [DOI: 10.1093/ndt/gfq647] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Soni S, Ernst RK, Muszyński A, Mohapatra NP, Perry MB, Vinogradov E, Carlson RW, Gunn JS. Francisella tularensis blue-gray phase variation involves structural modifications of lipopolysaccharide o-antigen, core and lipid a and affects intramacrophage survival and vaccine efficacy. Front Microbiol 2010; 1:129. [PMID: 21687776 PMCID: PMC3109528 DOI: 10.3389/fmicb.2010.00129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/28/2010] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a CDC Category A biological agent and a potential bioterrorist threat. There is no licensed vaccine against tularemia in the United States. A long-standing issue with potential Francisella vaccines is strain phase variation to a gray form that lacks protective capability in animal models. Comparisons of the parental strain (LVS) and a gray variant (LVSG) have identified lipopolysaccharide (LPS) alterations as a primary change. The LPS of the F. tularensis variant strain gains reactivity to F. novicida anti-LPS antibodies, suggesting structural alterations to the O-antigen. However, biochemical and structural analysis of the F. tularensis LVSG and LVS LPS demonstrated that LVSG has less O-antigen but no major O-antigen structural alterations. Additionally, LVSG possesses structural differences in both the core and lipid A regions, the latter being decreased galactosamine modification. Recent work has identified two genes important in adding galactosamine (flmF2 and flmK) to the lipid A. Quantitative real-time PCR showed reduced transcripts of both of these genes in the gray variant when compared to LVS. Loss of flmF2 or flmK caused less frequent phase conversion but did not alter intramacrophage survival or colony morphology. The LVSG strain demonstrated an intramacrophage survival defect in human and rat but not mouse macrophages. Consistent with this result, the LVSG variant demonstrated little change in LD50 in the mouse model of infection. Furthermore, the LVSG strain lacks the protective capacity of F. tularensis LVS against virulent Type A challenge. These data suggest that the LPS of the F. tularensis LVSG phase variant is dramatically altered. Understanding the mechanism of blue to gray phase variation may lead to a way to inhibit this variation, thus making future F. tularensis vaccines more stable and efficacious.
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Davenport A, Anker SD, Mebazaa A, Palazzuoli A, Vescovo G, Bellomo R, Ponikowski P, Anand I, Aspromonte N, Bagshaw S, Berl T, Bobek I, Cruz DN, Daliento L, Haapio M, Hillege H, House A, Katz N, Maisel A, Mankad S, McCullough P, Ronco F, Shaw A, Sheinfeld G, Soni S, Zamperetti N, Zanco P, Ronco C. ADQI 7: the clinical management of the Cardio-Renal syndromes: work group statements from the 7th ADQI consensus conference. Nephrol Dial Transplant 2010; 25:2077-2089. [DOI: 10.1093/ndt/gfq252] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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McCullough PA, Haapio M, Mankad S, Zamperetti N, Massie B, Bellomo R, Berl T, Anker SD, Anand I, Aspromonte N, Bagshaw SM, Bobek I, Cruz DN, Daliento L, Davenport A, Hillege H, House AA, Katz N, Maisel A, Mebazaa A, Palazzuoli A, Ponikowski P, Ronco F, Shaw A, Sheinfeld G, Soni S, Vescovo G, Zanco P, Ronco C, Berl T. Prevention of cardio-renal syndromes: workgroup statements from the 7th ADQI Consensus Conference. Nephrol Dial Transplant 2010; 25:1777-84. [DOI: 10.1093/ndt/gfq180] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Menon M, Soni S, Kusunam S, Bajaj S, Muoio V, Molmenti E, Jhaveri K, Bhaskaran M. 193: Elevated Human Chorionic Gonadotrophin (HCG) Levels in Patients With Chronic Kidney Disease. Am J Kidney Dis 2010. [DOI: 10.1053/j.ajkd.2010.02.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Mohapatra NP, Soni S, Rajaram MVS, Dang PMC, Reilly TJ, El-Benna J, Clay CD, Schlesinger LS, Gunn JS. Francisella acid phosphatases inactivate the NADPH oxidase in human phagocytes. THE JOURNAL OF IMMUNOLOGY 2010; 184:5141-50. [PMID: 20348422 DOI: 10.4049/jimmunol.0903413] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Francisella tularensis contains four putative acid phosphatases that are conserved in Francisella novicida. An F. novicida quadruple mutant (AcpA, AcpB, AcpC, and Hap [DeltaABCH]) is unable to escape the phagosome or survive in macrophages and is attenuated in the mouse model. We explored whether reduced survival of the DeltaABCH mutant within phagocytes is related to the oxidative response by human neutrophils and macrophages. F. novicida and F. tularensis subspecies failed to stimulate reactive oxygen species production in the phagocytes, whereas the F. novicida DeltaABCH strain stimulated a significant level of reactive oxygen species. The DeltaABCH mutant, but not the wild-type strain, strongly colocalized with p47(phox) and replicated in phagocytes only in the presence of an NADPH oxidase inhibitor or within macrophages isolated from p47(phox) knockout mice. Finally, purified AcpA strongly dephosphorylated p47(phox) and p40(phox), but not p67(phox), in vitro. Thus, Francisella acid phosphatases play a major role in intramacrophage survival and virulence by regulating the generation of the oxidative burst in human phagocytes.
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House AA, Anand I, Bellomo R, Cruz D, Bobek I, Anker SD, Aspromonte N, Bagshaw S, Berl T, Daliento L, Davenport A, Haapio M, Hillege H, McCullough P, Katz N, Maisel A, Mankad S, Zanco P, Mebazaa A, Palazzuoli A, Ronco F, Shaw A, Sheinfeld G, Soni S, Vescovo G, Zamperetti N, Ponikowski P, Ronco C. Definition and classification of Cardio-Renal Syndromes: workgroup statements from the 7th ADQI Consensus Conference. Nephrol Dial Transplant 2010; 25:1416-20. [DOI: 10.1093/ndt/gfq136] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Skeens M, Soni S, Pai V, Bajwa R, Pietryga D, Gross T, Termuhlen A. Case Control Study Of Levetiracetam Vs. Fosphenytoin For Seizure Prophylaxis In Children Receiving Busulfan (BU) For Hematopoietic Stem Cell Transplantation (HSCT). Biol Blood Marrow Transplant 2010. [DOI: 10.1016/j.bbmt.2009.12.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Skeens M, Pai V, Garee A, Bajwa R, Gross T, Termuhlen A, Soni S. Twice Daily Intravenous Tacrolimus (FK-506) Is A Safe And Effective Graft vs. Host Disease (GVHD) Prophylaxis For Pediatric Allogeneic Hematopoietic Stem Cell (HSCT) Recipients. Biol Blood Marrow Transplant 2010. [DOI: 10.1016/j.bbmt.2009.12.518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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69
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Soni S. Asperger Syndrome and Alcohol--Drinking to Cope? By Matthew Tinsley and Sarah Hendricks. Alcohol Alcohol 2010. [DOI: 10.1093/alcalc/agp076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Chiu HC, Soni S, Kulp SK, Curry H, Wang D, Gunn JS, Schlesinger LS, Chen CS. Eradication of intracellular Francisella tularensis in THP-1 human macrophages with a novel autophagy inducing agent. J Biomed Sci 2009; 16:110. [PMID: 20003180 PMCID: PMC2801672 DOI: 10.1186/1423-0127-16-110] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 12/09/2009] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Autophagy has been shown recently to play an important role in the intracellular survival of several pathogenic bacteria. In this study, we investigated the effect of a novel small-molecule autophagy-inducing agent, AR-12, on the survival of Francisella tularensis, the causative bacterium of tularemia in humans and a potential bioterrorism agent, in macrophages. METHODS AND RESULTS Our results show that AR-12 induces autophagy in THP-1 macrophages, as indicated by increased autophagosome formation, and potently inhibits the intracellular survival of F. tularensis (type A strain, Schu S4) and F. novicida in macrophages in association with increased bacterial co-localization with autophagosomes. The effect of AR-12 on intracellular F. novicida was fully reversed in the presence of the autophagy inhibitor, 3-methyl adenine or the lysosome inhibitor, chloroquine. Intracellular F. novicida were not susceptible to the inhibitory activity of AR-12 added at 12 h post-infection in THP-1 macrophages, and this lack of susceptibility was independent of the intracellular location of bacteria. CONCLUSION Together, AR-12 represents a proof-of-principle that intracellular F. tularensis can be eradicated by small-molecule agents that target innate immunity.
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Soni S, Alexander S, Verlander N, Saunders P, Richardson D, Fisher M, Ison C. The prevalence of urethral and rectal Mycoplasma genitalium and its associations in men who have sex with men attending a genitourinary medicine clinic. Sex Transm Infect 2009; 86:21-4. [PMID: 19843536 DOI: 10.1136/sti.2009.038190] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES To determine the prevalence of rectal and urethral Mycoplasma genitalium (MG) in men who have sex with men (MSM) attending a genitourinary medicine clinic and to measure its associations with symptoms, clinical signs, sexual behaviour and concomitant sexually transmitted infections (STI). METHODS MSM attending for STI screening were tested for MG using a real-time PCR assay that targets the MgPa gene. Data were collected on demographics, sexual behaviour, past STI history and clinical symptoms and signs. RESULTS 849 first-void urine and rectal specimens were collected from 438 MSM. The overall prevalence of MG in MSM was 6.6% with first-void urine positivity of 2.7% and rectal positivity of 4.4%. MG was significantly associated with HIV positivity (OR 7.6, 95% CI 3.2 to 18.7, p<0.001) in contrast to Chlamydia trachomatis (OR 1.5, 95% CI 0.5 to 4.1, p=0.4) and Neisseria gonorrhoeae (OR 1.7, 95% CI 0.7 to 3.8, p=0.194). MG was more prevalent than C trachomatis (p=0.15) and N gonorrhoeae (p=0.02) in this subgroup of HIV-positive MSM. Urethral infection was associated with dysuria (p<0.001) but there was no association between rectal infection and anorectal symptoms or signs. CONCLUSION Rates of MG are much higher in HIV-positive MSM than HIV-negative MSM at both urethral and rectal sites, and MG is more prevalent in HIV-positive MSM than other bacterial STI. Although the subclinical nature of MG in the rectum questions its significance, the high prevalence seen at this site could be a potential source of onward urethral transmission. Future work should assess the need for appropriate screening and treatment of MG infection in MSM, particularly those with HIV infection and high-risk sexual behaviour.
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Soni S, Aggarwal N, Dhaliwal L, Wangkheimayum S. Correlation of 2-Hour and 4-Hour Urinary Proteins with 24-Hours Proteinuria in Hospitalized Patients with Preeclampsia. Hypertens Pregnancy 2009; 28:109-18. [DOI: 10.1080/10641950802423996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Soni S, Ramesh N. HIV transmission within families in rural India. Int J STD AIDS 2009; 20:214-5. [DOI: 10.1258/ijsa.2009.009004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Soni S, Termuhlen A, Bajwa R, Clayton J, Montgomery M, Hardin D. Prevalence, Risk Factors and Management of Metabolic Syndrome After Stem Cell Transplantation In Pediatric Patients. Biol Blood Marrow Transplant 2009. [DOI: 10.1016/j.bbmt.2008.12.248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Clay CD, Soni S, Gunn JS, Schlesinger LS. Evasion of complement-mediated lysis and complement C3 deposition are regulated by Francisella tularensis lipopolysaccharide O antigen. THE JOURNAL OF IMMUNOLOGY 2008; 181:5568-78. [PMID: 18832715 DOI: 10.4049/jimmunol.181.8.5568] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The bacterium Francisella tularensis (Ft) is a potential weapon of bioterrorism when aerosolized. Macrophage infection is necessary for disease progression and efficient phagocytosis by human macrophages requires serum opsonization by complement. Microbial complement activation leads to surface deposition of a highly regulated protein complex resulting in opsonization or membrane lysis. The nature of complement component C3 deposition, i.e., C3b (opsonization and lysis) or C3bi (opsonization only) fragment deposition, is central to the outcome of activation. In this study, we examine the mechanisms of Ft resistance to complement-mediated lysis, C3 component deposition on the Ft surface, and complement activation. Upon incubation in fresh nonimmune human serum, Schu S4 (Ft subsp. tularensis), Fn (Ft subsp. novicida), and LVS (Ft subsp. holarctica live vaccine strain) were resistant to complement-mediated lysis, but LVSG and LVSR (LVS strains altered in surface carbohydrate structures) were susceptible. C3 deposition, however, occurred on all strains. Complement-susceptible strains had markedly increased C3 fragment deposition, including the persistent presence of C3b compared with C3bi, which indicates that C3b inactivation results in survival of complement-resistant strains. C1q, an essential component of the classical activation pathway, was necessary for lysis of complement-susceptible strains and optimal C3 deposition on all strains. Finally, use of Francisella LPS mutants confirmed O Ag as a major regulator of complement resistance. These data provide evidence that pathogenic Francisella activate complement, but are resistant to complement-mediated lysis in part due to limited C3 deposition, rapid conversion of surface-bound C3b to C3bi, and the presence of LPS O Ag.
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