63 results on '"R. Saksena"'
Search Results
2. Feasibility of reporting results of large randomised controlled trials to participants: experience from the Fluoxetine Or Control Under Supervision (FOCUS) trial
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Martin Dennis, D Cohen, A Thompson, M Smith, A Naqvi, Graham Ellis, A Khan, L Hunt, X Huang, J Andrews, J Foot, J Smith, S Wong, A Stevens, D Bailey, S Johnston, S Jones, R Robinson, A Johnson, S Williams, T Smith, A Ahmed, S Bloom, L Sekaran, D Singh, F Smith, R Greenwood, A Singh, R Brown, J White, S Smith, S Arif, S Ross, S Trippier, S Levy, B Patel, M Khan, A Thomas, S Brown, V Jones, D Wood, S Maguire, U Khan, P Nair, A Smith, G Hann, R Williams, M Cooper, S Jackson, M Hassan, P Kumar, A Metcalf, R Patel, A Wright, S Khan, A Bell, C Williams, M Robinson, K Jones, S Alam, R Shah, J Simpson, K Ali, K Miller, K Kennedy, S Ahmed, J Francis, L Thomas, M Scott, S Nelson, S Clayton, L Zhang, B Charles, P Lopez, A Fleming, C Lambert, A Shah, J Wong, David Burgess, L Wilson, A Siddiqui, S Kumar, A Hassan, D Cooke, M Williams, P Cooper, S Graham, S Morrison, M Holland, C Green, C Edwards, K Subramanian, K Patel, J Mitchell, J Stewart, S Keenan, C Duggan, S McKenna, R Murphy, M Ward, S Walker, S Lewis, R Jones, L Wright, M Edwards, N Sattar, J Mcgee, R Butler, M Wilkinson, S Das, C Kelly, R Cowan, C Brown, K Moore, L Denny, M Harrison, S Patel, R Rodriguez, J Allen, M Kalita, Gillian Mead, A Bowring, A Edwards, J Scott, J Drew, D Ward, L Dixon, K Burton, E Brown, E Epstein, R Miller, F Reid, A Jones, P Murphy, A Ali, N Ahmad, S Noor, C Leonard, A Nair, M Naeem, M Johnson, E Douglas, J Thompson, R Evans, C Jenkins, J Wilson, R Anderson, H Wilson, H Stone, J Ward, L Greenhalgh, P Walker, A Hill, K Stagg, S Naqvi, R Scott, M Hughes, P Jones, M Simpson, K Elliott, M Davy, S Young, Karen Innes, Pippa Tyrrell, A David, Steff Lewis, A Bwalya, C Buckley, S Kelly, C Thomas, I Kane, M Hussain, S Shah, J Roberts, D Morales, C McInnes, N Khan, N Weir, L Hill, J McLaughlin, K Kavanagh, R Clarke, P Thompson, J Price, J Ball, L Benton, E Walton, E Walker, L Burgess, K McCormick, L Wade, C Anderson, S Stevenson, R Blackburn, L Brown, B Clarke, T Khan, S Dhar, L Harrison, S Bell, D Buchanan, A Deary, J Drever, R Fraser, C Graham, K Innes, C McGill, D Perry, A Barugh, G Blair, Y Chun, E Maschauer, J Forbes, M Hackett, G Hankey, A House, E Lundström, Peter Sandercock, Judith Williamson, John Forbes, Graeme Hankey, Maree Hackett, Veronica Murray, Ray French, David Stott, Jonathan Emberson, P Sandercock, M MacLeod, F Sullivan, P Langhorne, H Rodgers, N Hunter, R Parakramawansha, A Fazal, P Taylor, W Rutherford, R Buchan, A MacRaild, R Paulton, S Burgess, D McGowan, J Skwarski, F Proudfoot, J Perry, J Bamford, C Bedford, D Waugh, E Veraque, M Kambafwile, L Makawa, P Smalley, M Randall, L Idrovo, T Thirugnana-Chandran, R Vowden, J Jackson, A Bhalla, C Tam, A Rudd, C Gibbs, J Birns, L Lee Carbon, E Cattermole, A Cape, L hurley, K Marks, S Kullane, N Smyth, E Giallombardo, C Eglinton, D Dellafera, P Reidy, M Pitt, L Sykes, A Frith, V Croome, J Duffy, M Hancevic, L Kerwood, C Narh, C Merritt, J Willson, T Jackson, H Bowler, C Kamara, J Howe, K Stocks, G Dunn, K Endean, F Claydon, S Duty, C Doyle, K Harkness, E Richards, M Meegada, A Maatouk, L Barron, K Dakin, R Lindert, A Majid, P Rana, C Brighouse-Johnson, J Greig, M Kyu, S Prasad, B Mclean, I Alam, Z Ahmed, C Roffe, S Brammer, A Barry, C Beardmore, K Finney, H Maguire, P Hollinshead, J Grocott, I Natarajan, J Chembala, R Sanyal, S Lijko, N Abano, A Remegoso, P Ferdinand, S Stevens, C Stephen, P Whitmore, A Butler, C Causley, R Varquez, G Muddegowda, R Carpio, J Hiden, H Denic, J Sword, F Hall, J Cageao, R Curwen, M James, P Mudd, C Roughan, H Kingwell, A Hemsley, C Lohan, S Davenport, T Chapter, M Hough, D Strain, K Gupwell, A Goff, E Cusack, S Todd, R Partridge, G Jennings, K Thorpe, J Stephenson, K Littlewood, M Barber, F Brodie, S Marshall, D Esson, I Coburn, F Ross, V Withers, E Bowie, H Barcroft, L Miller, P Willcoxson, M Keeling, M Donninson, D Daniel, J Coyle, M Elliott, P Wanklyn, J Wightman, E Iveson, A Porteous, N Dyer, M Haritakis, J Bell, C Emms, P Wood, P Cottrell, L Doughty, L Carr, C Anazodo, M O Neill, J Westmoreland, R Mir, C Donne, E Bamford, P Clark Brown, A Stanners, I Ghouri, A Needle, M Eastwood, M Carpenter, P Datta, R Davey, F Razik, G Bateman, J Archer, V Balasubramanian, L Jackson, R Bowers, J Ellam, K Norton, P Guyler, S Tysoe, P Harman, A Kundu, T Dowling, S Chandler, O Omodunbi, T Loganathan, S Kunhunny, D Sinha, M Sheppard, S Kelavkar, K Ng, A Ropun, L Kamuriwo, R Orath Prabakaran, E France, S Rashmi, D Mangion, C Constantin, S Markova, A Hardwick, J Borley, L De Michele Hock, T Lawrence, J Fletcher, K Netherton, R Spencer, H Palmer, M Soliman, S Leach, J Sharma, C Taylor, I Wahishi, A Fields, S Butler, J Hindle, E Watson, C Hewitt, C Cullen, D Hamill, Z Mellor, T Fluskey, V Hankin, A Keeling, R Durairaj, D Shackcloth, R Tangney, T Hlaing, V Sutton, J Ewing, C Patterson, H Ramadan, R Bellfield, U Hamid, M Hooley, R Ghulam, L Masters, W Gaba, O Quinn, M Tate, N Mohammed, S Sethuraman, L Alwis, K Bharaj, R Pattni, F Justin, M Chauhan, L Eldridge, S Mintias, J Palmones, C Holmes, L Guthrie, N Devitt, J Leonard, M Osborn, L Ball, A Steele, E Dodd, A Holloway, P Baker, I Penwarden, S Caine, S Clarke, L Dow, R Wynn-Williams, J Kennedy, A DeVeciana, P Mathieson, I Reckless, R Teal, U Schulz, G Ford, P Mccann, G Cluckie, G Howell, J Ayer, B Moynihan, R Ghatala, G Cloud, N Al-Samarrai, F Watson, T Adedoyin, N Chopra, L Choy, N Clarke, A Dainty, A Blight, J Selvarajah, W Smith, F Moreton, A Welch, D Kalladka, B Cheripelli, A Lush, S El Tawil, N Day, K Montgomery, H Hamilton, D Ritchie, S Ramachandra, K McLeish, B Badiani, M Abdul-Saheb, A Chamberlain, M Mpelembue, R Bathula, M Lang, J Devine, L Southworth, N Epie, E Owoyele, F Guo, A Oshodi, V Sudkeo, K Thavanesan, D Tiwari, C Ovington, E Rogers, R Bower, B Longland, O David, A Hogan, S Loganathan, C Cox, S Orr, M Keltos, K Rashed, B Williams-Yesson, J Board, S De Bruijn, C Vickers, S Board, J Allison, E Keeling, T Duckett, D Donaldson, C Barron, L Balian, T England, A Hedstrom, E Bedford, M Harper, E Melikyan, W Abbott, M Goldsworthy, M Srinivasan, I Mukherjee, U Ghani, A Yeomans, F Hurford, R Chapman, S Shahzad, N Motherwell, L Tonks, R Young, D Dutta, P Brown, F Davis, J Turfrey, M Obaid, B Cartwright, B Topia, J Spurway, C Hughes, S OConnell, K Collins, R Bakawala, K Chatterjee, T Webster, S Haider, P Rushworth, F Macleod, C Perkins, A Nallasivan, E Burns, S Leason, T Carter, S Seagrave, E Sami, S Parkinson, L Armstrong, S Mawer, G Darnbrook, C Booth, B Hairsine, S Williamson, F Farquhar, B Esisi, T Cassidy, B McClelland, G Mankin, M Bokhari, D Sproates, S Hurdowar, N Sukhdeep, S Razak, N Upton, A Hashmi, K Osman, K Fotherby, A Willberry, D Morgan, G Sahota, K Jennings-Preece, D Butler, K Kauldhar, F Harrington, A Mate, J Skewes, K Adie, K Bond, G Courtauld, C Schofield, L Lucas, A James, S Ellis, B Maund, L Allsop, C Brodie, E Driver, K Harris, M Drake, E Thomas, M Burn, A Hamilton, S Mahalingam, A Benford, D Hilton, A Misra, L Hazell, K Ofori, M Mathew, S Dayal, I Burn, D Bruce, R Burnip, R Hayman, P Earnshaw, P Gamble, S Dima, M Dhakal, G Rogers, L Stephenson, R Nendick, Y Pai, K Nyo, V Cvoro, M Couser, A Tachtatzis, K Ullah, R Cain, N Chapman, S Pound, S McAuley, D Hargroves, B Ransom, K Mears, K Griffiths, L Cowie, T Hammond, T Webb, I Balogun, H Rudenko, A Thomson, D Ceccarelli, A Gillian, E Beranova, A Verrion, N Chattha, N Schumacher, A Bahk, D Sims, R Tongue, M Willmot, C Sutton, E Littleton, J Khaira, S Maiden, J Cunningham, Y Chin, M Bates, K Ahlquist, J Breeds, T Sargent, L Latter, A Pitt Ford, T Levett, N Gainsborough, A Dunne, E Barbon, S Hervey, S Ragab, T Sandell, C Dickson, S Power, J Dube, N Evans, B Wadams, S Elitova, B Aubrey, T Garcia, J Mcilmoyle, C Dickinson, C Jeffs, J Howard, C Armer, J Frudd, A Potter, S Donaldson, D Collas, S Sundayi, L Denham, D Oza, M Bhandari, S Ispoglou, K Sharobeem, A Hayes, J Howard-Brown, S Shanu, S Billingham, G Howard, E Wood, V Pressly, P Crawford, H Burton, A Walters, J Marigold, R Said, C Allen, S Evans, S Egerton, J Hakkak, R Lampard, S Tsang, R Creeden, I Gartrell, F Price, J Pryor, A Hedges, L Moseley, L Mercer, E Warburton, D Handley, S Finlay, N Hannon, A Espanol, H Markus, D Chandrasena, J Sesay, D Hayden, H Hayhoe, J Macdonald, M Bolton, C Farron, E Amis, D Day, A Culbert, L Whitehead, S Crisp, J OConnell, E Osborne, R Beard, P Corrigan, L Mokoena, M Myint, R Krishnamurthy, A Azim, S Whitworth, A Nicolson, M Krasinska-Chavez, J Imam, S Chaplin, J Curtis, L Wood, A Byrne, C McGhee, A Smart, F Donaldson, J Blackburn, C Copeland, P Fitzsimmons, G Fletcher, A Manoj, P Cox, L Trainor, H Allsop, U Sukys, S Valentine, D Jarrett, K Dodsworth, M Wands, C Watkinson, W Golding, J Tandy, K Yip, C James, Y Davies, A Suttling, K Nagaratnam, N Mannava, N Haque, N Shields, K Preston, G Mason, K Short, G Uitenbosch, G Lumsdale, H Emsley, S Sultan, B Walmsley, D Doyle, A McLoughlin, L Hough, B Gregary, S Raj, A Maney, S Blane, G Gamble, A Hague, B Duran, R Whiting, M Harvey, J Homan, L Foote, L Graham, C Lane, L Kemp, J Rowe, H Durman, L Brotherton, N Hunt, A Whitcher, C Pawley, P Sutton, S Mcdonald, D Pak, A Wiltshire, J Balami, C Self, J Jagger, G Healey, M Crofts, A Chakrabarti, C Hmu, J Keshet-Price, G Ravenhill, C Grimmer, T Soe, I Potter, P Tam, M Langley, M Christie, J Irvine, A Joyson, F Annison, D Christie, C Meneses, V Taylor, J Furnace, H Gow, J Reid, Y Abousleiman, S Goshawk, J Purcell, T Beadling, S Collins, S Sangaralingham, E Munuswamy Vaiyapuri, M Landicho, Y Begum, S Mutton, J Lowe, I Wiggam, S Tauro, S Cuddy, B Wells, A Mohd Nor, N Persad, M Weinling, S Weatherby, D Lashley, A Pace, A Mucha, J Baker, M Marner, J Westcott, N Wilmshurst, D Chadha, M Fairweather, D Walstow, R Fong, M Krishnan, H Thompson Jones, C Lynda, C Clements, T Anjum, S Sharon, D Lynne, S Tucker, D Colwill, E Vasileiadis, A Parry, C Mason, M Holden, K Petrides, T Nishiyama, H Mehta, S Mumani, C Almadenboyle, S Carson, M Stirling, E Tenbruck, D Broughton, A Annamalai, D Tryambake, A Skotnicka, A Sigsworth, S Whitehouse, J Pagan, A Pusalkar, H Beadle, K Chan, P Dangri, A Asokanathan, A Rana, S Gohil, K Crabtree, A Cook, M Massyn, P Aruldoss, S Dabbagh, T Black, C Clarke, R Fennelly, L Nardone, V DiMartino, A Anthony, D Mead, M Tribbeck, B Affley, C Sunderland, E Young, L Goldenberg, P Wilkinson, L Abbott, R Nari, S Lock, A Shakhon, R Pereira, M DSouza, S Dunn, N Cron, A Mckenna, R Sivakumar, S Cook, J Ngeh, R Saksena, J Ketley-O'Donel, R Needle, E Chinery, L Howaniec, C Watchurst, R Erande, M Brezitski, N Passeron, E Elliott, N Oji, D Austin, A Banaras, C Hogan, T Corbett, M Kidd, G Hull, S Punekar, J Nevinson, H Penney, W Wareing, N Hayes, K Bunworth, L Connell, K Mahawish, G Drummond, N Sengupta, M Metiu, C Gonzalez, J Margalef, S Funnell, G Peters, I Chadbourn, H Proeschel, P Ashcroft, S Sharpe, P Cook, D Jenkinson, D Kelly, H Bray, G Gunathilagan, S Tilbey, S Abubakar, A Rajapakse, A Nasar, J Janbieh, L Otter, I Wynter, S Haigh, R Boulton, J Burgoyne, A Boulton, J Vassallo, A Hasan, L Orrell, S Qamar, D Leonard, E Hewitt, M Haque, J Awolesi, E Bradshaw, A Kent, A Hynes, E Nurse, S Raza, U Pallikona, B Edwards, G Morgan, H Tench, R Loosley, K Dennett, T Trugeon-Smith, D Robson, R Rayessa, A Abdul-Hamid, V Lowthorpe, K Mitchelson, E Clarkson, H Rhian, R Kirthivasan, J Topliffe, R Keskeys, F McNeela, E Bohannan, L Cooper, G Zachariah, F Cairns, T James, L Fergey, S Smolen, A Lyle, E Cannon, S Omer, S Mavinamane, S Meenakshisundaram, L Ranga, J Bate, M Hargreaves, S Dealing, S Amlani, G Gulli, M Hawkes-Blackburn, L Francis, S Holland, A Peacocke, J Amero, M Burova, O Speirs, S Brotheridge, S Al Hussayni, H Lyon, C Hare, J Featherstone, M Goorah, J Walford, D Rusk, D Sutton, F Patel, S Duberley, K Hayes, E Ahmed El Nour, S Dyer, E Temlett, J Paterson, S Honour, C Box, R Furness, E Orugun, H Crowther, R Glover, C Brewer, S Thornthwaite, M Sein, K Haque, L Bailey, E Gibson, L Brookes, K Rotchell, K Waltho, C Lindley, P Harlekar, C Culmsee, L Booth, J Ritchie, N Mackenzie, J Barker, M Haley, D Cotterill, L Lane, D Simmons, R Warinton, G Saunders, H Dymond, S Kidd, C Little, Y Neves-Silva, B Nevajda, M Villaruel, U Umasankar, A Man, N Gadi, N Christmas, R Ladner, R Rangasamy, G Butt, W Alvares, M Power, S Hagan, K Dynan, D Wilson, S Crothers, B Wroath, G Douris, D Vahidassr, B Gallen, C McGoldrick, M Bhattad, J Putteril, R Gallifent, E Makanju, M Lepore, C McRedmond, L Arundell, A Goulding, K Kawafi, P Jacob, L Turner, N Saravanan, L Johnson, D Morse, R Namushi, S Humphrey, M Salehin, S Tinsley, T Jones, L Garcia-Alen, L Kalathil, N Gautam, J Horton, J Meir, E Margerum, A Ritchings, K Amor, V Nadarajan, J Laurence, S Fung Lo, S Melander, P Nicholas, E Woodford, G McKenzie, V Le, J Crause, P OMahony, C Orefo, C McDonald, E Osikominu, G Appiatse, A Wardale, M Augustin, R Luder, M Bhargava, G Bhome, V Johnson, D Chesser, H Bridger, E Murali, A Burns, J Graham, M Duffy, E Pitcher, J Gaylard, J Newman, S Punnoose, S Oakley, V Murray, C Bent, R Walker, K Purohit, A Rees, S Besley, O Chohan, L Argandona, L Cuenoud, H Hassan, E Erumere, A OCallaghan, O Redjep, G Auld, P Gompertz, A Song, R Hungwe, H Kabash, T Tarkas, G Livingstone, F Butler, S Bradfield, L Gordon, J Schmit, A Wijewardane, C Medcalf, T Edmunds, R Wills, and C Peixoto
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Medicine - Abstract
Objectives Informing research participants of the results of studies in which they took part is viewed as an ethical imperative. However, there is little guidance in the literature about how to do this. The Fluoxetine Or Control Under Supervision trial randomised 3127 patients with a recent acute stroke to 6 months of fluoxetine or placebo and was published in the Lancet on 5 December 2018. The trial team decided to inform the participants of the results at exactly the same time as the Lancet publication, and also whether they had been allocated fluoxetine or placebo. In this report, we describe how we informed participants of the results.Design In the 6-month and 12-month follow-up questionnaires, we invited participants to provide an email address if they wished to be informed of the results of the trial. We re-opened our trial telephone helpline between 5 December 2018 and 31 March 2019.Setting UK stroke services.Participants 3127 participants were randomised. 2847 returned 6-month follow-up forms and 2703 returned 12-month follow-up forms; the remaining participants had died (380), withdrawn consent or did not respond.Results Of those returning follow-up questionnaires, a total of 1845 email addresses were provided and a further 50 people requested results to be sent by post. Results were sent to all email and postal addresses provided; 309 emails were returned unrecognised. Seventeen people replied, of whom three called the helpline and the rest responded by email.Conclusion It is feasible to disseminate results of large trials to research participants, though only around 60% of those randomised wanted to receive the results. The system we developed was efficient and required very little resource, and could be replicated by trialists in the future.Trial registration number ISRCTN83290762; Post-results.
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- 2020
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3. Prevalence of transfusion-transmitted viral pathogens among health-care workers and risk mitigation programme in a paediatric tertiary care hospital
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R. Saksena, Charu Nayyar, and Vikas Manchanda
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0301 basic medicine ,Microbiology (medical) ,medicine.medical_specialty ,Blood transfusion ,Health Personnel ,medicine.medical_treatment ,Hepatitis C virus ,viruses ,health care facilities, manpower, and services ,Health-care workers ,030106 microbiology ,Immunology ,education ,lcsh:QR1-502 ,medicine.disease_cause ,Risk Assessment ,Microbiology ,Virus ,lcsh:Microbiology ,Tertiary Care Centers ,03 medical and health sciences ,0302 clinical medicine ,Immunology and Microbiology (miscellaneous) ,Occupational Exposure ,Environmental health ,Health care ,Blood-Borne Pathogens ,Prevalence ,medicine ,Humans ,Immunology and Allergy ,Blood Transfusion ,Intensive care medicine ,Risk management ,Hepatitis B virus ,General Immunology and Microbiology ,business.industry ,virus diseases ,Hospitals, Pediatric ,Infectious Diseases ,viral pathogens ,030211 gastroenterology & hepatology ,business ,Risk assessment ,Risk Reduction Behavior ,occupational risks - Abstract
The health-care workers (HCWs) are at an occupational risk of exposure to blood-borne pathogens, mainly, HIV, hepatitis B virus (HBV) and hepatitis C virus. HBV is currently the only blood-borne virus for which a vaccine is available. All health-care institutions must encourage the HCWs to undergo screening for blood-borne pathogens.
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- 2017
4. Use of valence delta, δv in the molecular connectivity calculations and correlation with molar refraction
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A. R. Saksena, Das, Sunanda, and Gupta, Arti
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chelates ,Molecular connectivity ,ligands ,conformational analysis ,molar refraction ,organometallics - Abstract
Department of Chemistry, C.M.P. Degree College (University of Allahabad), Allahabad-211 002, Uttar Pradesh, India E-mail : guptarti@yahoo.co.in Manuscript received 4 February 2008, revised 18 August 2008, accepted 19 December 2008 Molecular connectivity calculations have been carried out for highly anisotropic bidentate ligands (C2v symmetry), organometallic substrates of the formulae, R2MX2 (where R is an alkyl group and X is a halogen atom) and organometallic chelates of the formulae, R2MLx (where L is a bidentate ligand). Multiple Chi, m\({\chi_t^v}\) with reference to valence delta, δv have been calculated for the hydrogen suppressed graphs (skeletal structures) for each molecule and have been correlated with molar refractions. These correlations will play a vital role in the SAR studies of biologically active molecules.
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- 2009
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5. Candidaemia and Central Line-Associated Candidaemia in a Network of Indian ICUs: Impact of COVID-19 Pandemic.
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Mathur P, Srivastav S, Thakur AK, Parveen R, Puraswani M, Srivastava AK, Chakrabarti A, Rodrigues C, Balaji V, Ray P, Biswal M, Wattal C, Venkatesh V, Sethuraman N, Bhattacharya S, Nag VL, Tak V, Behera B, Goel N, Iravane J, Mukherjee S, Ray R, Singh SK, Mukhopadhyay C, Michael JS, Fomda BA, Chelliah J, Shetty A, Karuna T, Ningombam A, Kumar S, Soni KD, Sagar S, Aggrawal R, Gupta D, Singh GP, Bindra A, Farooque K, Purwar S, Khadanga S, Vandana KE, Varma M, Deotale V, Das P, Lohiya R, Prasad A, Gupta PK, Omar BJ, Aggarwal A, Baqal S, Devi KR, Singh LC, Chatterji S, Goel G, Mukherjee S, Ramanathan YV, Sonowal A, Verma P, Mahapatra A, Hallur V, Gaikwad UN, Bhargava A, Padmaja K, Bheerappa N, Jain V, Bhatia P, Singh K, Khera D, Gupta N, Paul H, Verma S, Arshad Z, Jhaj R, Malik S, Thirunarayan MA, Raj HJ, Gupta P, Himanshu D, Rudramurthy SM, Nath R, Gur R, Lyngdoh NM, Lyngdoh C, Devi S, Malhotra S, Gaind R, Saksena R, Sharma R, and Walia K
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- Humans, India epidemiology, Male, Middle Aged, Female, Adult, SARS-CoV-2, Aged, Catheter-Related Infections epidemiology, Catheter-Related Infections microbiology, Pandemics, COVID-19 epidemiology, Candidemia epidemiology, Intensive Care Units statistics & numerical data, Cross Infection epidemiology
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Background and Objectives: Candidaemia is a potentially life-threatening emergency in the intensive care units (ICUs). Surveillance using common protocols in a large network of hospitals would give meaningful estimates of the burden of candidaemia and central line associated candidaemia in low resource settings. We undertook this study to understand the burden and epidemiology of candidaemia in multiple ICUs of India, leveraging the previously established healthcare-associated infections (HAI) surveillance network. Our aim was also to assess the impact that the pandemic of COVID-19 had on the rates and associated mortality of candidaemia., Methods: This study included adult patients from 67 Indian ICUs in the AIIMS-HAI surveillance network that conducted BSI surveillance in COVID-19 and non-COVID-19 ICUs during and before the COVID-19 pandemic periods. Hospitals identified healthcare-associated candidaemia and central line associated candidaemia and reported clinical and microbiological data to the network as per established and previously published protocols., Results: A total of 401,601 patient days and 126,051 central line days were reported during the study period. A total of 377 events of candidaemia were recorded. The overall rate of candidaemia in our network was 0.93/1000 patient days. The rate of candidaemia in COVID-19 ICUs (2.52/1000 patient days) was significantly higher than in non-COVID-19 ICUs (1.05/patient days) during the pandemic period. The rate of central line associated candidaemia in COVID-19 ICUs (4.53/1000 central line days) was also significantly higher than in non-COVID-19 ICUs (1.73/1000 central line days) during the pandemic period. Mortality in COVID-19 ICUs associated with candidaemia (61%) was higher than that in non-COVID-19 ICUs (41%). A total of 435 Candida spp. were isolated. C. tropicalis (26.7%) was the most common species. C. auris accounted for 17.5% of all isolates and had a high mortality., Conclusion: Patients in ICUs with COVID-19 infections have a much higher risk of candidaemia, CLAC and its associated mortality. Network level data helps in understanding the true burden of candidaemia and will help in framing infection control policies for the country., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)
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- 2024
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6. Varicella zoster virus outbreak in a long-term care unit of a tertiary care hospital in northern India.
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Saksena R, Thomas BJ, Das R, Nagpal S, Suri PR, Wadhwa RK, Choudhary A, Gaind R, and Gupta E
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- Adult, Humans, Chickenpox epidemiology, India epidemiology, Long-Term Care, Varicella Zoster Virus Infection epidemiology, Cross Infection epidemiology, Cross Infection virology, Disease Outbreaks, Herpesvirus 3, Human isolation & purification, Tertiary Care Centers
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Nosocomial outbreak of varicella zoster virus (VZV) has been reported when susceptible individuals encounter a case of chicken pox or shingles. A suspected VZV outbreak was investigated in a 50-bedded in-patient facility of Physical Medicine and Rehabilitation in a tertiary care multispecialty hospital. A 30-year-old female patient admitted with Pott's spine was clinically diagnosed with chicken pox on 31 December 2022. The following week, four more cases were identified in the same ward. All cases were diagnosed as laboratory-confirmed varicella zoster infection by PCR. Primary case was a housekeeping staff who was clinically diagnosed with chicken pox 3 weeks prior (9 December 2022). He returned to work on eighth day of infection (17 December 2022) after apparent clinical recovery but before the lesions had crusted over. Thirty-one HCWs were identified as contacts a and three had no evidence of immunity. Two of these susceptible HCWs had onset of chickenpox shortly after first dose of VZV vaccination was inoculated. All cases recovered after treatment with no reported complications. VZV infection is highly contagious in healthcare settings with susceptible populations. Prompt identification of cases and implementation of infection prevention and control measures like patient isolation and vaccination are essential for the containment of outbreaks.
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- 2024
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7. Risk factors and outcome associated with the acquisition of MDR linezolid-resistant Enterococcus faecium: a report from tertiary care centre.
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Rani V, Aye NK, Saksena R, Dabi KC, Mannan MA, and Gaind R
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- Humans, Linezolid pharmacology, Linezolid therapeutic use, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Case-Control Studies, Tertiary Care Centers, Enterococcus, Carbapenems therapeutic use, Risk Factors, Enterococcus faecium genetics, Gram-Positive Bacterial Infections drug therapy, Gram-Positive Bacterial Infections epidemiology, Gram-Positive Bacterial Infections microbiology
- Abstract
Objective: The aim of the study was to determine the resistance profile of linezolid-resistant Enterococcus faecium (LREfm) and to investigate risk factors and outcomes associated with LREfm infections., Material and Methods: A prospective case-control study was undertaken (2019 to 2022) and included 202 patients with LREfm infections (cases) and 200 controls with LSEfm infections. Clinical data was prospectively collected and analysed for risk factors and outcomes. Antimicrobial susceptibility was performed, and resistance profile was studied using WHOnet., Results: Risk factors associated with LREfm infection were site of infection UTI (OR 5.87, 95% CI 2.59-13.29, p ≤ 0.001), prior use of carbapenem (OR 2.85 95% CI 1.62-5.02, p ≤ 0.001) and linezolid (OR 10.13, 95% CI 4.13-24.82, p ≤ 0.001), use of central line (OR 5.54, 95% CI 2.35-13.09, p ≤ 0.001), urinary catheter (OR 0.29, 95% CI 0.12-0.70, p ≤ 0.001) and ventilation (OR 14.87, 95% CI 7.86-28.11, p ≤ 0.007). The hospital stay 8-14 days (< 0.001) prior to infection and the mortality rate (p = 0.003) were also significantly high among patients with LREfm infections. Linezolid and vancomycin resistance coexisted; further, MDR, XDR and PDR phenotypes were significantly higher among LREfm., Conclusion: This study provided insight into epidemiology of MDR LREfm in a setting where linezolid use is high. The main drivers of infections with LREfm are multiple, including use of carbapenems and linezolid. Invasive procedures and increased hospital stay facilitate spread through breach in infection control practises. As therapeutic options are limited, ongoing surveillance of LREfm and VRE is critical to guide appropriate use of linezolid and infection control policies., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
- Published
- 2024
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8. Live to eat and eat to live longer.
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Adler A and Saksena R
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- Energy Intake, Longevity
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- 2023
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9. Defining Polysaccharide-Specific Antibody Targets against Vibrio cholerae O139 in Humans following O139 Cholera and following Vaccination with a Commercial Bivalent Oral Cholera Vaccine, and Evaluation of Conjugate Vaccines Targeting O139.
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Kamruzzaman M, Kelly M, Charles RC, Harris JB, Calderwood SB, Akter A, Biswas R, Kaisar MH, Bhuiyan TR, Ivers LC, Ternier R, Jerome JG, Pfister HB, Lu X, Soliman SE, Ruttens B, Saksena R, Mečárová J, Čížová A, Qadri F, Bystrický S, Kováč P, Xu P, and Ryan ET
- Subjects
- Adolescent, Adult, Aged, Animals, Child, Cholera immunology, Cholera Vaccines administration & dosage, Convalescence, Disease Models, Animal, Female, Hospitalization statistics & numerical data, Humans, Immunoglobulin A blood, Immunoglobulin G blood, Immunoglobulin M blood, Male, Mice, Middle Aged, Vaccination, Vaccines, Combined administration & dosage, Vaccines, Combined immunology, Vaccines, Conjugate administration & dosage, Vaccines, Conjugate immunology, Vaccines, Conjugate standards, Young Adult, Antibodies, Bacterial blood, Cholera prevention & control, Cholera Vaccines immunology, O Antigens immunology, Vibrio cholerae O139 immunology
- Abstract
Cholera caused by Vibrio cholerae O139 could reemerge, and proactive development of an effective O139 vaccine would be prudent. To define immunoreactive and potentially immunogenic carbohydrate targets of Vibrio cholerae O139, we assessed immunoreactivities of various O-specific polysaccharide (OSP)-related saccharides with plasma from humans hospitalized with cholera caused by O139, comparing responses to those induced in recipients of a commercial oral whole-cell killed bivalent (O1 and O139) cholera vaccine (WC-O1/O139). We also assessed conjugate vaccines containing selected subsets of these saccharides for their ability to induce protective immunity using a mouse model of cholera. We found that patients with wild-type O139 cholera develop IgM, IgA, and IgG immune responses against O139 OSP and many of its fragments, but we were able to detect only a moderate IgM response to purified O139 OSP-core, and none to its fragments, in immunologically naive recipients of WC-O1/O139. We found that immunoreactivity of O139-specific polysaccharides with antibodies elicited by wild-type infection markedly increase when saccharides contain colitose and phosphate residues, that a synthetic terminal tetrasaccharide fragment of OSP is more immunoreactive and protectively immunogenic than complete OSP, that native OSP-core is a better protective immunogen than the synthetic OSP lacking core, and that functional vibriocidal activity of antibodies predicts in vivo protection in our model but depends on capsule thickness. Our results suggest that O139 OSP-specific responses are not prominent following vaccination with a currently available oral cholera vaccine in immunologically naive humans and that vaccines targeting V. cholerae O139 should be based on native OSP-core or terminal tetrasaccharide. IMPORTANCE Cholera is a severe dehydrating illness of humans caused by Vibrio cholerae serogroup O1 or O139. Protection against cholera is serogroup specific, and serogroup specificity is defined by O-specific polysaccharide (OSP). Little is known about immunity to O139 OSP. In this study, we used synthetic fragments of the O139 OSP to define immune responses to OSP in humans recovering from cholera caused by V. cholerae O139, compared these responses to those induced by the available O139 vaccine, and evaluated O139 fragments in next-generation conjugate vaccines. We found that the terminal tetrasaccharide of O139 is a primary immune target but that the currently available bivalent cholera vaccine poorly induces an anti-O139 OSP response in immunologically naive individuals.
- Published
- 2021
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10. Acute stroke showing cerebral infarcts and microbleeds in a 31-year-old man with COVID-19 pneumonia.
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Planinc D, El-Rekaby A, Sivakumar R, Saksena R, and Ngeh J
- Subjects
- Adult, Betacoronavirus, COVID-19, Humans, Male, Pandemics, Respiration, Artificial, Risk Factors, SARS-CoV-2, Troponin blood, Cerebral Hemorrhage etiology, Cerebral Infarction etiology, Coronavirus Infections complications, Pneumonia, Viral complications, Stroke etiology
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- 2020
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11. Fatal pulmonary infection by trimethoprim-sulfamethoxazole resistant Nocardia otitidiscaviarum: report of two cases and review.
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Saksena R, Rynga D, Rajan S, Gaind R, Dawar R, Sardana R, Sen MK, and Suri JC
- Subjects
- Aged, Anti-Bacterial Agents therapeutic use, Drug Therapy, Combination, Fatal Outcome, Female, Humans, Male, Nocardia isolation & purification, Respiratory Tract Infections microbiology, Sulfamethoxazole therapeutic use, Trimethoprim therapeutic use, Drug Resistance, Multiple, Bacterial, Nocardia Infections diagnosis, Nocardia Infections drug therapy, Respiratory Tract Infections diagnosis, Respiratory Tract Infections drug therapy
- Abstract
Introduction: Nocardia otitidiscaviarum is a rare cause of human infections, mostly causing cutaneous and lymphocutaneous infections of mild severity. We report two cases of fatal pulmonary infection caused by Nocardia otitidiscaviarum in elderly patients., Methodology: Case 1: A 70-year old woman presented with fever and cough with expectoration for a month. On physical examination, she had tachypnea and inspiratory crepitations in bilateral basal regions. Case 2: A 74-year old man presented with productive cough with foul smelling expectoration, fever and shortness of breath for one week. On examination, he had tachypnea, bilateral wheezing and inspiratory crepitations. In both cases, sputum was sent to microbiology laboratory. On direct microscopy Gram-positive, finely branching filaments were observed which were acid fast with 1% sulphuric acid. Chalky white opaque wrinkled colonies with musty basement type odour were seen on blood agar. Both patients were treated empirically with trimethoprim-sulfamethoxazole for Nocardia infection after notification of microscopy findings however both expired on Day 2 and Day 5 of admission, respectively. Both isolates were susceptible to amikacin, linezolid, ciprofloxacin and gentamicin. They were resistant to trimethoprim-sulfamethoxazole, ampicillin, amoxicillin-clavulanic acid, erythromycin, and imipenem. Based on biochemical identification and antimicrobial susceptibility pattern, the organism was identified as Nocardia otitidiscaviarum. The identification was confirmed using MALDI-TOF (Vitek MS, Biomerieux, France)., Conclusion: Our report highlights the importance of early identification of Nocardia to species level to improve treatment outcomes especially in critically ill patients. Mass spectrometry can become an integral part of diagnostic algorithms for nocardiosis., Competing Interests: No Conflict of Interest is declared, (Copyright (c) 2020 Rushika Saksena, Dabet Rynga, Santosh Rajan, Rajni Gaind, Reetika Dawar, Raman Sardana, Manas Kamal Sen, Jagdish Chandra Suri.)
- Published
- 2020
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12. Can sputum gram stain be used to predict lower respiratory tract infection and guide empiric antimicrobial treatment: Experience from a tertiary care hospital.
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Gunasekaran J, Saksena R, Jain M, and Gaind R
- Subjects
- Adolescent, Adult, Community-Acquired Infections diagnosis, Female, Humans, Male, Middle Aged, Tertiary Care Centers, Young Adult, Bacteria isolation & purification, Cross Infection diagnosis, Gentian Violet, Phenazines, Pneumonia, Bacterial diagnosis, Sputum microbiology, Staining and Labeling methods
- Abstract
Background: The mortality associated with lower respiratory tract infection is high. Indiscriminate use of antimicrobials leads to alteration of respiratory tract flora and development of multi-drug resistance. Rapid diagnostic tests to confirm infection can guide the clinicians about antimicrobial treatment. So the present study was planned to evaluate the role of direct gram stain examination as a rapid and simple test to help clinicians for appropriate patient management., Methods: The present study was conducted on 1000 respiratory specimens which were processed using conventional microbiological techniques. Gram stain smear and culture results were compared statistically to assess the sensitivity, specificity, positive and negative predictive value. The agreement between gram stain smear examination and culture was calculated using kappa statistics., Results: Potential pathogens were obtained from 28 of 209 deeply coughed out sputum samples (13.3%) and from 19 of 315 saliva mixed sputum samples (6%). Out of 473 tracheal aspirates, 115 (24.3%) had potential pathogens. The sensitivity for predicting infection was higher for good quality sputum samples (54%) as compared to poor quality sputum samples (37%). The gram stain and culture of tracheal samples had a good agreement for predicting infection whereas there was only moderate agreement for sputum sample., Conclusion: Gram stain smear examination from respiratory samples can be used to guide empiric antibiotic therapy pending final culture sensitivity results if the attending physicians ensure appropriate sample collection and transport. In absence of these supportive measures smear examination should not be relied upon for empiric treatment., (Copyright © 2019. Published by Elsevier B.V.)
- Published
- 2019
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13. Structure-Immunogenicity Relationship of α- and β-Tetrasaccharide Glycoforms from Bacillus anthracis Exosporium and Fragments Thereof.
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De Ricco R, Ventura CL, Carboni F, Saksena R, Kováč P, and Adamo R
- Subjects
- Animals, Antibodies, Bacterial immunology, Bacillus anthracis immunology, Female, Glycoconjugates immunology, Isomerism, Membrane Glycoproteins immunology, Mice, Inbred BALB C, Spores, Bacterial immunology, Structure-Activity Relationship, Bacillus anthracis metabolism, Oligosaccharides immunology, Polysaccharides, Bacterial immunology, Rhamnose metabolism
- Abstract
The tetrasaccharide (2- O -methyl-4-(3-hydroxy-3-methylbutamido)-4,6-dideoxy-α-d-glucopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-l-rhamnopyranose) from the major exosporium protein (BclA) of Bacillus anthracis has been proposed as a target for development of diagnostics and immune therapy or prophylaxis. While the immunodominant character of the anthrose residue has been previously elucidated, the role of the stereochemical configuration of the downstream rhamnose is unknown. Because the linkage of this residue to the GlcNAc bridging the glycan and the protein is lost during isolation of the tetrasaccharide, its α- and β-glycoforms have been synthesized. Herein, we prepared neoglycoconjugates from a series of fragments of the tetrasaccharide, including the complete α- and β-tetrasaccharide glycoforms, a 2-demethoxylated version of the α-tetrasaccharide, and the α- and β-trirhamnosides and CRM
197 . By immunization of mice, we showed that the anti α- and β-tetrasaccharide serum equally recognized both glycoforms. In contrast the sera produced following immunization with the α- and β-trirhamnoside fragments exhibited higher recognition for their own antigens than for their anomeric counterparts. The anti α- and β-tetrasaccharide sera recognized Sterne spores in a comparable fashion. ΔBclA spores not expressing the major exosporium protein were also recognized by the same sera, while mutants that produced the carbohydrate antigen with deletion of either rhamnose or anthrose were not. The tetrasaccharide could, therefore, be expressed in proteins other than BlcA. This work proves that α- and β-tetrasaccharide are equally potent immunogens.- Published
- 2018
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14. High prevalence of fluoroquinolone resistance amongst commensal flora of antibiotic naïve neonates: a study from India.
- Author
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Saksena R, Gaind R, Sinha A, Kothari C, Chellani H, and Deb M
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Enterobacteriaceae classification, Enterobacteriaceae genetics, Enterobacteriaceae isolation & purification, Feces microbiology, Female, Humans, India, Infant, Newborn, Male, Microbial Sensitivity Tests, Plasmids, Prevalence, Anti-Bacterial Agents pharmacology, Drug Resistance, Bacterial, Enterobacteriaceae drug effects, Fluoroquinolones pharmacology, Gastrointestinal Tract microbiology
- Abstract
Background: The emergence of resistance amongst commensal flora is a serious threat to the community. However, there is paucity of data regarding antibiotic resistance in commensals in the absence of antibiotic pressure., Methods: Altogether, 100 vaginally delivered antibiotic naïve exclusively breastfed neonates were selected. Stool samples collected on day (D)1, D21 and D60 of birth were cultured. Enterobacteriaceae isolates were screened for nalidixic acid (NA) and ciprofloxacin susceptibility as per CLSI guidelines. In 28 randomly selected neonates, isolates (n=92) resistant to NA and ciprofloxacin were characterized for the presence of plasmid-mediated quinolone resistance (PMQR) genes (qnrA, qnrB and qnrS, qepAand aac(6')-Ib-cr) and mutations in the quinolone resistance determining region (QRDR) of gyrA and parC genes by specific primers and confirmed by sequencing., Results: A total of 343 Enterobacteriaceae were isolated from 100 neonates. On D1, 58 % of neonates were colonized with at least one Enterobacteriaceae predominantly E. coli. Overall resistance to NA was 60 % but ciprofloxacin resistance increased significantly from 15 % (14/96) on D1 to 38 % (50/132) on D60 (P-value <0.001). The predominant mechanism of fluoroquinolone resistance was mutation in gyrA (n=49) with or without PMQR. PMQR carrying isolates increased more than fivefold from D1 to D60., Conclusion: A high level of fluoroquinolone resistance in gut flora of antibiotic naïve and exclusively breastfed neonates suggests a rampant rise of resistance in the community. The source of resistance genes on D1 is probably maternal flora acquired at birth. High load of PMQR genes in commensal flora are a potential source of spread to pathogenic organisms.
- Published
- 2018
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15. Systematic review and meta-analysis of remotely delivered interventions using self-monitoring or tailored feedback to change dietary behavior.
- Author
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Teasdale N, Elhussein A, Butcher F, Piernas C, Cowburn G, Hartmann-Boyce J, Saksena R, and Scarborough P
- Subjects
- Databases, Factual, Exercise, Feedback, Humans, Randomized Controlled Trials as Topic, Self-Control, Diet, Health Behavior
- Abstract
Background: Self-monitoring (SM) of diet and tailored feedback (TF) have been suggested as tools for changing dietary behavior. New technologies allow users to monitor behavior remotely, potentially improving reach, adherence, and outcomes., Objective: We conducted a systematic literature review and meta-analysis to address the following question: are remotely delivered standalone (i.e., no human contact) interventions that use SM or TF effective in changing eating behaviors?, Design: Five databases were searched in October 2016 (updated in September 2017). Only randomized controlled trials published after 1990 were included. Trials could include any adult population with no history of disordered eating which delivered an SM or TF intervention without direct contact and recorded actual dietary consumption as an outcome. Three assessors independently screened the search results. Two reviewers extracted the study characteristics, intervention details, and outcomes, and assessed risk of bias using the Cochrane tool. Results were converted to standardized mean differences and incorporated into a 3-level (individuals and outcomes nested in studies) random effects meta-analysis., Results: Twenty-six studies containing 21,262 participants were identified. The majority of the studies were judged to be unclear or at high risk of bias. The meta-analysis showed dietary improvement in the intervention group compared to the control group with a standardized mean difference of 0.17 (95% CI: 0.10, 0.24; P < 0.0001). The I2 statistic for the meta-analysis was 0.77, indicating substantial heterogeneity in results. A "one study removed" sensitivity analysis showed that no single study excessively influenced the results., Conclusions: Standalone interventions containing self-regulatory methods have a small but significant effect on dietary behavior, and integrating these elements could be important in future interventions. However, there was substantial variation in study results that could not be explained by the characteristics we explored, and there were risk-of-bias concerns with the majority of studies.
- Published
- 2018
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16. Early treatment failure in concurrent dengue and mixed malaria species infection with suspected resistance to artemisinin combination therapy from a tertiary care center in Delhi: a case report.
- Author
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Saksena R, Matlani M, Singh V, Kumar A, Anveshi A, Kumar D, and Gaind R
- Abstract
Background: Concurrent dengue and mixed malaria infections in a single patient present with overlapping clinical manifestations which pose a diagnostic challenge and management dilemma in areas of common endemicities., Methods: We report a case of a young male who tested positive for both Plasmodium vivax and Plasmodium falciparum along with dengue infection. He showed signs of early treatment failure to artemisinin combination therapy (artesunate with sulfadoxine+pyrimethamine). Molecular analysis for the drug resistance genes viz: chloroquine resistance ( pfcrt ), multidrug resistance ( pfmdr-1 ), sulfadoxine ( pfdhps ), pyrimethamine ( pfdhfr ), and artemisinin resistance ( keltch 13 ) was performed., Results: A rise in parasitemia from <2% to 5% was observed after 3 days of treatment. Mutations in pfcrt , pfmdr-1 , pfdhfr , and pfdhps genes were detected as a possible cause of treatment failure., Conclusion: Increased severity, overlapping symptoms, and suspected resistance to treatment warrants a multidimensional diagnostic approach and diligent therapeutic monitoring., Competing Interests: Disclosure The authors report no conflicts of interest in this work.
- Published
- 2017
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17. Overweight and Obesity in Children under 5 Years: Surveillance Opportunities and Challenges for the WHO European Region.
- Author
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Jones RE, Jewell J, Saksena R, Ramos Salas X, and Breda J
- Abstract
Background: Many children who have overweight or obesity before puberty can develop obesity in early adulthood, which is associated with increased morbidity and mortality. The preschool years (ages 0-5) represents a point of opportunity for children to be active, develop healthy eating habits, and maintain healthy growth. Surveillance of childhood overweight and obesity in this age group can help inform future policies and interventions., Objective: To review and report available prevalence data in WHO European Region Member States and determine how many countries can accurately report on rates of overweight and obesity in children under 5 years., Methods: We conducted a rapid review of studies reporting on overweight and obesity prevalence in children ages 0-5 in the WHO European region member states from 1998 to 2015., Results: Currently, 35 of the 53 member states have data providing prevalence rates for overweight and obesity for children under 5 years. There was little consistency in study methods, impacting comparability across countries. The prevalence of overweight and obesity in children under 5 years ranges from 1 to 28.6% across member states., Conclusion: Although measuring overweight and obesity in this age group may be challenging, there is an opportunity to leverage existing surveillance resources in the WHO European Region.
- Published
- 2017
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18. Prevalence of transfusion-transmitted viral pathogens among health-care workers and risk mitigation programme in a paediatric tertiary care hospital.
- Author
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Nayyar C, Saksena R, and Manchanda V
- Subjects
- Hospitals, Pediatric, Humans, Prevalence, Risk Assessment, Tertiary Care Centers, Blood Transfusion, Blood-Borne Pathogens isolation & purification, Health Personnel, Occupational Exposure, Risk Reduction Behavior
- Abstract
The health-care workers (HCWs) are at an occupational risk of exposure to blood-borne pathogens, mainly, HIV, hepatitis B virus (HBV) and hepatitis C virus. HBV is currently the only blood-borne virus for which a vaccine is available. All health-care institutions must encourage the HCWs to undergo screening for blood-borne pathogens.
- Published
- 2017
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19. Tubular organ epithelialisation.
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Saksena R, Gao C, Wicox M, and de Mel A
- Abstract
Hollow, tubular organs including oesophagus, trachea, stomach, intestine, bladder and urethra may require repair or replacement due to disease. Current treatment is considered an unmet clinical need, and tissue engineering strategies aim to overcome these by fabricating synthetic constructs as tissue replacements. Smart, functionalised synthetic materials can act as a scaffold base of an organ and multiple cell types, including stem cells can be used to repopulate these scaffolds to replace or repair the damaged or diseased organs. Epithelial cells have not yet completely shown to have efficacious cell-scaffold interactions or good functionality in artificial organs, thus limiting the success of tissue-engineered grafts. Epithelial cells play an essential part of respective organs to maintain their function. Without successful epithelialisation, hollow organs are liable to stenosis, collapse, extensive fibrosis and infection that limit patency. It is clear that the source of cells and physicochemical properties of scaffolds determine the successful epithelialisation. This article presents a review of tissue engineering studies on oesophagus, trachea, stomach, small intestine, bladder and urethral constructs conducted to actualise epithelialised grafts., Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
- Published
- 2016
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20. Six-year susceptibility trends and effect of revised Clinical Laboratory Standards Institute breakpoints on ciprofloxacin susceptibility reporting in typhoidal Salmonellae in a tertiary care paediatric hospital in Northern India.
- Author
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Saksena R, Nayyar C, and Manchanda V
- Subjects
- Hospitals, Pediatric, Humans, India, Nalidixic Acid pharmacology, Prospective Studies, Tertiary Care Centers, Anti-Bacterial Agents pharmacology, Ciprofloxacin pharmacology, Drug Resistance, Bacterial, Microbial Sensitivity Tests standards, Salmonella paratyphi A drug effects, Salmonella typhi drug effects
- Abstract
The antimicrobial trends over 6 years were studied, and the effect of revised Clinical Laboratory Standards Institute (CLSI) breakpoints (2012) for ciprofloxacin susceptibility reporting in typhoidal Salmonellae was determined. A total of 874 (95.4%) isolates were nalidixic acid-resistant (NAR). Using the CLSI 2011 guidelines (M100-S21), 585 (66.9%) isolates were ciprofloxacin susceptible. The susceptibility reduced to 11 (1.25%) isolates when interpreted using 2012 guidelines (M100-S22). Among the forty nalidixic acid susceptible (NAS) Salmonellae, susceptibility to ciprofloxacin decreased from 37 isolates (M100-S21) to 12 isolates (M100-S22). The 25 cases which appeared resistant with newer guidelines had a minimum inhibitory concentration (MIC) range between 0.125 and 0.5 μg/ml. MIC50 for the third generation cephalosporins varied between 0.125 and 0.5 μg/ml over 6 years whereas MIC90 varied with a broader range of 0.19-1 μg/ml. The gap between NAR and ciprofloxacin-resistant strains identified using 2011 guidelines has been reduced; however, it remains to be seen whether additional NAS, ciprofloxacin-resistant isolates are truly resistant to ciprofloxacin by other mechanisms of resistance.
- Published
- 2016
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21. Tuberculous lymphadenitis: Comparison of cytomorphology, Ziehl-Neelsen staining, and rapid mycobacterial culture at a pediatric superspecialty hospital.
- Author
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Mahana S, Tomar R, Agrawal R, Saksena R, Manchanda V, and Gupta R
- Abstract
Background: To evaluate and compare the role of Ziehl-Neelsen (ZN) staining and mycobacterial culture in diagnosis of tuberculous lymphadenitis., Materials and Methods: A total of 56 fine needle aspirations (FNAs) from patients who were clinically suspected to have tuberculous lymphadenitis were included. Acid-fast Bacilli detection was attempted by ZN staining on smears as well as culture on Middlebrook 7H9 broth. Percentage positivity of both smears and culture was calculated., Results: Of the 56 cases, 46 showed cytomorphological features consistent with tuberculosis (TB). The most common pattern was only necrosis in 37 cases followed by necrotizing granulomas in 13 cases. ZN-stained smears were positive in 40 cases while culture was positive in only 27 cases. The highest smear and culture positivity was noted in cases with only necrosis. In six cases, diagnosis of TB was made on culture alone since smear was negative in these cases., Conclusion: FNA is a reliable technique for early and accurate diagnosis of tuberculous lymphadenitis in many cases. Mycobacterial culture by newer rapid techniques can assist in bacillary detection in smear-negative cases and also allows for drug sensitivity testing. Hence, culture should be resorted to in such cases.
- Published
- 2016
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22. Prioritisation of sugar to tackle obesity.
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Saksena R and Scherdel L
- Subjects
- Cardiovascular Diseases epidemiology, Cardiovascular Diseases etiology, Cardiovascular Diseases prevention & control, Chronic Disease, Diabetes Mellitus epidemiology, Diabetes Mellitus etiology, Diabetes Mellitus prevention & control, Dietary Sucrose administration & dosage, Dietary Sucrose standards, Energy Intake, Guidelines as Topic, Humans, Musculoskeletal Diseases epidemiology, Musculoskeletal Diseases etiology, Musculoskeletal Diseases prevention & control, Obesity complications, Obesity epidemiology, Risk Factors, World Health Organization, Dietary Sucrose adverse effects, Global Health standards, Health Priorities, Obesity prevention & control
- Published
- 2015
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23. Bordetella trematum bacteremia in an infant: a cause to look for.
- Author
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Saksena R, Manchanda V, and Mittal M
- Subjects
- Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Bacteremia microbiology, Bordetella Infections microbiology, Female, Fluoroquinolones therapeutic use, Humans, Infant, Macrolides therapeutic use, Microbial Sensitivity Tests, Treatment Outcome, Bacteremia diagnosis, Bacteremia pathology, Bordetella classification, Bordetella isolation & purification, Bordetella Infections diagnosis, Bordetella Infections pathology
- Abstract
Bordetella trematum spp. nov. has been isolated from wounds, ear infections and diabetic ulcers. We report a case of a 7-month-old infant with fever, vomiting and abnormal body movements with bacteremia caused by this novel species. The infant responded to fluoroquinolone and macrolide combination therapy.
- Published
- 2015
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24. The power of genes: a case of unusually severe systemic toxicity after localized hepatic chemoembolization with irinotecan-eluted microspheres for metastatic colon cancer.
- Author
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Cruz JE, Saksena R, Jabbour SK, Nosher JL, Hermes-DeSantis E, and Moss RA
- Subjects
- Aged, 80 and over, Antineoplastic Agents, Phytogenic administration & dosage, Camptothecin administration & dosage, Camptothecin adverse effects, Colonic Neoplasms surgery, Female, Humans, Irinotecan, Liver Neoplasms secondary, Microspheres, Mutation, Neutropenia chemically induced, Polymorphism, Genetic, Antineoplastic Agents, Phytogenic adverse effects, Camptothecin analogs & derivatives, Chemoembolization, Therapeutic, Colonic Neoplasms pathology, Glucuronosyltransferase genetics, Liver Neoplasms drug therapy
- Abstract
Objective: To report a case of systemic irinotecan toxicity following regional transarterial chemoembolization with drug-eluting beads loaded with irinotecan (DEBIRI-TACE) in a patient later found to have a homozygous mutation for UGT1A1*28., Case Summary: An 80-year-old woman presented with a cecal colon cancer with synchronous metastases to the liver. After resection of the primary tumor, the patient underwent DEBIRI-TACE with 100 mg of irinotecan to treat the residual disease in the liver. A week after this procedure, the patient developed grade 4 neutropenia, and later, alopecia. Eventually, it was found that the patient had a mutation of UDP glucuronosyltransferase 1 family polypeptide A1 (UGT1A1), which provided a reasonable explanation for the observed reaction., Discussion: The toxic effects of irinotecan are well understood. Patients with genetic polymorphisms of the genes encoding for the enzyme UGT1A1 may have increased incidence of irinotecan-associated toxicities because of decreased clearance of the active metabolite SN38 via the glucuronidation pathway. To date, there have been limited publications describing systemic adverse events following TACE or DEBIRI-TACE and, based on a thorough literature search, none following these procedures in patients with UGT1A1 polymorphisms. Based on the scoring results of the Naranjo algorithm (7), we are confident in attributing the observed reaction to the patient's genetic polymorphism., Conclusion: Although genetic testing prior to the initiation of irinotecan therapy is not currently recommended, assessment of UGT1A1 polymorphism is warranted when severe adverse events typical of systemic therapy manifest following DEBIRI-TACE., (© The Author(s) 2014.)
- Published
- 2014
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25. Chemoenzymatic synthesis of immunogenic meningococcal group C polysialic acid-tetanus Hc fragment glycoconjugates.
- Author
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McCarthy PC, Saksena R, Peterson DC, Lee CH, An Y, Cipollo JF, and Vann WF
- Subjects
- Amino Acid Sequence, Animals, Campylobacter jejuni immunology, Meningococcal Vaccines immunology, Mice, Molecular Sequence Data, Neisseria meningitidis immunology, Peptide Fragments immunology, Sialic Acids immunology, Tetanus Toxin immunology, Vaccines, Conjugate immunology, Meningococcal Vaccines chemistry, Peptide Fragments chemistry, Sialic Acids chemistry, Tetanus Toxin chemistry, Vaccines, Conjugate chemistry
- Abstract
Vaccination with meningococcal glycoconjugate vaccines has decreased the incidence of invasive meningitis worldwide. These vaccines contain purified capsular polysaccharides attached to a carrier protein. Because of derivatization chemistries used in the process, conjugation of polysaccharide to protein often results in heterogeneous mixtures. Well-defined vaccines are needed to determine the relationship between vaccine structure and generated immune response. Here, we describe efforts to produce well-defined vaccine candidates by chemoenzymatic synthesis. Chemically synthesized lactosides were substrates for recombinant sialyltransferase enzymes from Camplyobacter jejuni and Neisseria meningitidis serogroup C. These resulting oligosialic acids have the same α(2-9) sialic acid repeat structure as Neisseria polysaccharide capsule with the addition of a conjugatable azide aglycon. The degree of polymerization (DP) of carbohydrate products was controlled by inclusion of the inhibitor CMP-9-deoxy-NeuNAc. Polymers with estimated DP < 47 (median DP 25) and DP < 100 (median DP 51) were produced. The receptor binding domain of the tetanus toxin protein (TetHc) was coupled as a carrier to the enzymatically synthesized oligosialic acids. Recombinant TetHc was derivatized with an alkyne squarate. Protein modification sites were determined by trypsin proteolysis followed by LC/MS-MS(E) analysis of peptides. Oligosialic acid azides were conjugated to modified TetHc via click chemistry. These chemoenzymatically prepared glycoconjugates were reactive in immunoassays with specific antibodies against either group C polysaccharide or TetHc. Sera of mice immunized with oligosialic acid-TetHc glycoconjugates contained much greater levels of polysaccharide-reactive IgG than the sera of control mice receiving unconjugated oligosialic acids. There was no apparent difference between glycoconjugates containing oligosaccharides of DP < 47 and DP < 100. These results suggest that chemoenzymatic synthesis may provide a viable method for making defined meningococcal vaccine candidates.
- Published
- 2013
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26. Clinical evidence of the efficacy of everolimus and its potential in the treatment of breast cancer.
- Author
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Saksena R and Wong ST
- Abstract
The PI3K/Akt/mTOR (phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin) pathway regulates several key cellular functions and its dysregulation creates an environment that promotes tumorigenesis as well as resistance to therapy. The mTOR inhibitor everolimus has emerged as a promising agent in the treatment of breast cancer and was recently approved in combination with exemestane for advanced hormone receptor-positive disease after progression on a nonsteroidal aromatase inhibitor. Everolimus may also be effective in combination with cytotoxic and human epidermal growth factor receptor-2-directed therapies for the treatment of other subtypes of breast cancer. This paper highlights preclinical and clinical data that have emerged on the role of mTOR inhibition in breast cancer. Although generally well tolerated, everolimus carries a unique side effect profile of which both patients and providers should be made aware. Recommendations related to the administration of everolimus in the clinical setting are also discussed.
- Published
- 2013
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27. High-throughput printing via microvascular multinozzle arrays.
- Author
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Hansen CJ, Saksena R, Kolesky DB, Vericella JJ, Kranz SJ, Muldowney GP, Christensen KT, and Lewis JA
- Subjects
- Polymethyl Methacrylate, Pressure, Printing instrumentation
- Abstract
Microvascular multinozzle arrays are designed and fabricated for high-throughput printing of functional materials. Ink-flow uniformity within these multigeneration, bifurcating microchannel arrays is characterized by computer modeling and microscopic particle image velocimetry (micro-PIV) measurements. Both single and dual multinozzle printheads are produced to enable rapid printing of multilayered periodic structures over large areas (≈1 m(2))., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2013
- Full Text
- View/download PDF
28. Revealing the glycation sites in synthetic neoglycoconjugates formed by conjugation of the antigenic monosaccharide hapten of Vibrio cholerae O1, serotype Ogawa with the BSA protein carrier using LC-ESI-QqTOF-MS/MS.
- Author
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Jahouh F, Saksena R, Kováč P, and Banoub J
- Subjects
- Amino Acid Sequence, Animals, Cattle, Chromatography, Liquid, Glycosylation, Lysine chemistry, Models, Molecular, Molecular Sequence Data, Nanotechnology, Peptide Hydrolases chemistry, Spectrometry, Mass, Electrospray Ionization, Tandem Mass Spectrometry, Antigens, Bacterial chemistry, Glycoconjugates chemistry, Haptens chemistry, Serum Albumin, Bovine chemistry, Vibrio cholerae O1 chemistry
- Abstract
In this manuscript, we present the determination of glycation sites in synthetic neoglycoconjugates formed by conjugation of the antigenic monosaccharide hapten of Vibrio cholerae O1 serotype Ogawa to BSA using nano- liquid chromatography electrospray ionization quadrupole time-of-flight tandem mass spectroscopy (LC-ESI-QqTOF-MS/MS). The matrix-assisted laser desorption/ionization-TOF/TOF-MS/MS analyses of the tryptic digests of the glycoconjugates having a hapten:BSA ratio of 4.3:1, 6.6:1 and 13.2:1 revealed only three glycation sites, on the following lysine residues: Lys 235, Lys 437 and Lys 455. Digestion of the neoglycoconjugates with the proteases trypsin and GluC V8 gave complementary structural information and was shown to maximize the number of recognized glycation sites. Here, we report identification of 20, 27 and 33 glycation sites using LC-ESI-QqTOF-MS/MS analysis of a series of synthetic neoglycoconjugates with a hapten:BSA ratio of, respectively, 4.3:1, 6.6:1 and 13.2:1. We also tentatively propose that all the glycated lysine residues are located mainly near the outer surface of the protein., (Copyright © 2012 John Wiley & Sons, Ltd.)
- Published
- 2012
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29. Transcutaneous immunization with a Vibrio cholerae O1 Ogawa synthetic hexasaccharide conjugate following oral whole-cell cholera vaccination boosts vibriocidal responses and induces protective immunity in mice.
- Author
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Tarique AA, Kalsy A, Arifuzzaman M, Rollins SM, Charles RC, Leung DT, Harris JB, Larocque RC, Sheikh A, Bhuiyan MS, Saksena R, Clements JD, Calderwood SB, Qadri F, Kovác P, and Ryan ET
- Subjects
- Adjuvants, Immunologic administration & dosage, Administration, Cutaneous, Administration, Oral, Animals, Antibodies, Bacterial blood, Antigens, Bacterial administration & dosage, Bacterial Toxins administration & dosage, Blood Bactericidal Activity, Cholera immunology, Cholera Toxin administration & dosage, Cholera Vaccines administration & dosage, Disease Models, Animal, Enterotoxins administration & dosage, Escherichia coli Proteins administration & dosage, Feces chemistry, Female, Immunization, Secondary methods, Immunoglobulin A analysis, Immunoglobulin A blood, Immunoglobulin G blood, Immunoglobulin M blood, Injections, Subcutaneous, Mice, Oligosaccharides administration & dosage, Survival Analysis, Vaccines, Attenuated administration & dosage, Vaccines, Attenuated immunology, Vaccines, Conjugate administration & dosage, Vaccines, Conjugate immunology, Antigens, Bacterial immunology, Cholera prevention & control, Cholera Vaccines immunology, Oligosaccharides immunology, Vibrio cholerae O1 immunology
- Abstract
A shortcoming of currently available oral cholera vaccines is their induction of relatively short-term protection against cholera compared to that afforded by wild-type disease. We were interested in whether transcutaneous or subcutaneous boosting using a neoglycoconjugate vaccine made from a synthetic terminal hexasaccharide of the O-specific polysaccharide of Vibrio cholerae O1 (Ogawa) coupled to bovine serum albumin as a carrier (CHO-BSA) could boost lipopolysaccharide (LPS)-specific and vibriocidal antibody responses and result in protective immunity following oral priming immunization with whole-cell cholera vaccine. We found that boosting with CHO-BSA with immunoadjuvantative cholera toxin (CT) or Escherichia coli heat-labile toxin (LT) following oral priming with attenuated V. cholerae O1 vaccine strain O395-NT resulted in significant increases in serum anti-V. cholerae LPS IgG, IgM, and IgA (P < 0.01) responses as well as in anti-Ogawa (P < 0.01) and anti-Inaba (P < 0.05) vibriocidal titers in mice. The LPS-specific IgA responses in stool were induced by transcutaneous (P < 0.01) but not subcutaneous immunization. Immune responses following use of CT or LT as an adjuvant were comparable. In a neonatal mouse challenge assay, immune serum from boosted mice was associated with 79% protective efficacy against death. Our results suggest that transcutaneous and subcutaneous boosting with a neoglycoconjugate following oral cholera vaccination may be an effective strategy to prolong protective immune responses against V. cholerae.
- Published
- 2012
- Full Text
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30. Glycation sites in neoglycoglycoconjugates from the terminal monosaccharide antigen of the O-PS of Vibrio cholerae O1, serotype Ogawa, and BSA revealed by matrix-assisted laser desorption-ionization tandem mass spectrometry.
- Author
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Jahouh F, Saksena R, Aiello D, Napoli A, Sindona G, Kováč P, and Banoub JH
- Subjects
- Animals, Cattle, Glycoconjugates metabolism, Glycosylation, Haptens chemistry, Lysine chemistry, O Antigens metabolism, Vibrio cholerae O1 metabolism, Glycoconjugates chemistry, O Antigens chemistry, Serum Albumin, Bovine chemistry, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods, Tandem Mass Spectrometry methods, Vibrio cholerae O1 chemistry
- Abstract
We present the MALDI-TOF/TOF-MS analyses of various hapten-bovine serum albumin (BSA) neoglycoconjugates obtained by squaric acid chemistry coupling of the spacer-equipped, terminal monosaccharide of the O-specific polysaccharide of Vibrio cholerae O1, serotype Ogawa, to BSA. These analyses allowed not only to calculate the molecular masses of the hapten-BSA neoglycoconjugates with different hapten-BSA ratios (4.3, 6.6 and 13.2) but, more importantly, also to localize the covalent linkages (conjugation sites) between the hapten and the carrier protein. Determination of the site of glycation was based on comparison of the MALDI-TOF/TOF-MS analysis of the peptides resulting from the digestion of BSA with similar data resulting from the digestion of BSA glycoconjugates, followed by sequencing by MALDI-TOF/TOF-MS/MS of the glycated peptides. The product-ion scans of the protonated molecules were carried out with a MALDI-TOF/TOF-MS/MS tandem mass spectrometer equipped with a high-collision energy cell. The high-energy collision-induced dissociation (CID) spectra afforded product ions formed by fragmentation of the carbohydrate hapten and amino acid sequences conjugated with fragments of the carbohydrate hapten. We were able to identify three conjugation sites on lysine residues (Lys235, Lys437 and Lys455). It was shown that these lysine residues are very reactive and bind lysine specific reagents. We presume that these Lys residues belong to those that are considered to be sterically more accessible on the surface of the tridimensional structure. The identification of the y-series product ions was very useful for the sequencing of various peptides. The series of a- and b-product ions confirmed the sequence of the conjugated peptides., (Copyright © 2010 John Wiley & Sons, Ltd.)
- Published
- 2010
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31. Multimeric bivalent immunogens from recombinant tetanus toxin HC fragment, synthetic hexasaccharides, and a glycopeptide adjuvant.
- Author
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Bongat AF, Saksena R, Adamo R, Fujimoto Y, Shiokawa Z, Peterson DC, Fukase K, Vann WF, and Kovác P
- Subjects
- Carbohydrate Conformation, Carbohydrate Sequence, Glycoconjugates chemical synthesis, Glycoconjugates chemistry, Glycopeptides chemistry, Molecular Sequence Data, Oligosaccharides chemistry, Peptide Fragments chemistry, Recombinant Proteins chemistry, Tetanus Toxin chemistry, Adjuvants, Immunologic chemical synthesis, Glycopeptides immunology, Oligosaccharides immunology, Peptide Fragments immunology, Tetanus Toxin immunology, Vaccines, Synthetic immunology
- Abstract
Using recombinant tetanus toxin H(C) fragment (rTT-H(C)) as carrier, we prepared multimeric bivalent immunogens featuring the synthetic hexasaccharide fragment of O-PS of Vibrio cholerae O:1, serotype Ogawa, in combination with either the synthetic hexasaccharide fragment of O-PS of Vibrio cholerae O:1, serotype Inaba, or a synthetic disaccharide tetrapeptide peptidoglycan fragment as adjuvant. The conjugation reaction was effected by squaric acid chemistry and monitored in virtually real time by SELDI-TOF MS. In this way, we could prepare well-defined immunogens with predictable carbohydrate-carrier ratio, whose molecular mass and the amount of each saccharide attached could be independently determined. The ability to prepare such neoglycoconjugates opens unprecedented possibilities for preparation of conjugate vaccines for bacterial diseases from synthetic carbohydrates.
- Published
- 2010
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32. Synthesis, conjugation, and immunological evaluation of the serogroup 6 pneumococcal oligosaccharides.
- Author
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Parameswar AR, Park IH, Saksena R, Kovác P, Nahm MH, and Demchenko AV
- Subjects
- Animals, Antibodies, Bacterial immunology, Cattle, Enzyme-Linked Immunosorbent Assay, Epitopes metabolism, Glycoconjugates chemical synthesis, Mice, Mice, Inbred C57BL, Oligosaccharides chemical synthesis, Oligosaccharides chemistry, Polysaccharides, Bacterial chemistry, Rabbits, Serotyping, Serum Albumin, Bovine chemistry, Streptococcus pneumoniae classification, Glycoconjugates immunology, Oligosaccharides immunology, Polysaccharides, Bacterial immunology, Streptococcus pneumoniae immunology
- Abstract
The first synthesis of the newly discovered oligosaccharide of pneumococcal serotype 6C and its spacer-containing analogue is reported. Conjugation of the spacer-containing oligosaccharides of pneumococcal saccharides 6A, 6B, 6C and derivatives thereof with bovine serum albumin (BSA) protein carrier was carried out by using squaric-acid approach to obtain the oligosaccharide-protein conjugates in excellent yields. The conjugates have been tested with a rabbit antiserum pool (Pool B) used for pneumococcal serotyping. The results showed that synthetic carbohydrate conjugates express epitopes found in native capsular polysaccharides of serotypes 6A, 6B, and 6C.
- Published
- 2009
- Full Text
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33. Development of antibodies against anthrose tetrasaccharide for specific detection of Bacillus anthracis spores.
- Author
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Kuehn A, Kovác P, Saksena R, Bannert N, Klee SR, Ranisch H, and Grunow R
- Subjects
- Animals, Anthrax microbiology, Antibodies, Bacterial metabolism, Bacillus anthracis immunology, Deoxyglucose immunology, Female, Membrane Glycoproteins metabolism, Mice, Mice, Inbred BALB C, Microscopy, Immunoelectron, Rabbits, Spores, Bacterial immunology, Spores, Bacterial ultrastructure, Amino Sugars immunology, Anthrax immunology, Antibodies, Bacterial immunology, Bacillus anthracis isolation & purification, Deoxyglucose analogs & derivatives, Membrane Glycoproteins immunology, Spores, Bacterial isolation & purification
- Abstract
Methods for the immunological detection of Bacillus anthracis in various environmental samples and the discrimination of B. anthracis from other members of the B. cereus group are not yet well established. To generate specific discriminating antibodies, we immunized rabbits, mice, and chickens with inactivated B. anthracis spores and, additionally, immunized rabbits and mice with the tetrasaccharide beta-Ant-(1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-L-Rhap. It is a constituent of the exosporium glycoprotein BclA and contains the newly discovered sugar anthrose 2-O-methyl-4-(3-hydroxy-3-methylbutamido)-4,6-dideoxy-beta-D-glucose. The BclA protein is a major component of the exosporium of B. anthracis spores and is decorated by the tetrasaccharide indicated above. The anthrose-containing tetrasaccharide chain seems to be highly specific for B. anthracis, which makes it a key biomarker for the detection of these spores. The different immunizations led to anthrose-reactive polyclonal and monoclonal antibodies which were analyzed by various methods to characterize their ability to discriminate between B. anthracis and other Bacillus spp. Multiple applications, such as enzyme-linked immunosorbent assay, indirect immunofluorescence assay, and electron microscopy, revealed the specificities of the polyclonal and monoclonal antibodies generated for B. anthracis spore detection. All polyclonal antibodies were able to correctly identify the B. anthracis strains tested and showed only minimal cross-reactivities with other Bacillus strains. Moreover, the antibodies generated proved functional in a new capture assay for B. anthracis spores and could therefore be useful for the detection of spores in complex samples.
- Published
- 2009
- Full Text
- View/download PDF
34. Transcutaneous immunization with a synthetic hexasaccharide-protein conjugate induces anti-Vibrio cholerae lipopolysaccharide responses in mice.
- Author
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Rollenhagen JE, Kalsy A, Saksena R, Sheikh A, Alam MM, Qadri F, Calderwood SB, Kovác P, and Ryan ET
- Subjects
- Adjuvants, Immunologic administration & dosage, Adjuvants, Immunologic pharmacology, Administration, Cutaneous, Animals, Cholera Toxin administration & dosage, Cholera Toxin pharmacology, Cholera Vaccines adverse effects, Immunoglobulin A blood, Immunoglobulin G blood, Mice, Mice, Inbred BALB C, Microbial Viability, O Antigens chemistry, O Antigens immunology, Serum Albumin, Bovine chemistry, Vaccines, Conjugate administration & dosage, Vaccines, Conjugate immunology, Vaccines, Synthetic administration & dosage, Vaccines, Synthetic adverse effects, Vaccines, Synthetic immunology, Vibrio cholerae O1 immunology, Antibodies, Bacterial blood, Cholera Vaccines administration & dosage, Cholera Vaccines immunology, Vibrio cholerae immunology
- Abstract
Antibodies specific for Vibrio cholerae lipopolysaccaride (LPS) are common in humans recovering from cholera, and constitute a primary component of the vibriocidal response, a serum complement-mediated bacteriocidal response correlated with protection against cholera. In order to determine whether transcutaneous immunization (TCI) with a V. cholerae neoglycoconjugate (CHO-BSA) comprised of a synthetic terminal hexasaccharide of the O-specific polysaccharide of V. cholerae O1 (Ogawa) conjugated with bovine serum albumin (BSA) could induce anti-V. cholerae LPS and vibriocidal responses, we applied CHO-BSA transcutaneously in the presence or absence of the immune adjuvant cholera toxin (CT) to mice. Transcutaneously applied neoglycoconjugate elicited prominent V. cholerae specific LPS IgG responses in the presence of CT, but not IgM or IgA responses. CT applied on the skin induced strong IgG and IgA serum responses. TCI with neoglycoconjugate did not elicit detectable vibriocidal responses, protection in a mouse challenge assay, or stool anti-V. cholerae IgA responses, irrespective of the presence or absence of CT. Our results suggest that transcutaneously applied synthetic V. cholerae neoglycoconjugate is safe and immunogenic, but predominantly induces systemic LPS responses of the IgG isotype.
- Published
- 2009
- Full Text
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35. Application of carbohydrate microarray technology for the detection of Burkholderia pseudomallei, Bacillus anthracis and Francisella tularensis antibodies.
- Author
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Parthasarathy N, Saksena R, Kováč P, Deshazer D, Peacock SJ, Wuthiekanun V, Heine HS, Friedlander AM, Cote CK, Welkos SL, Adamovicz JJ, Bavari S, and Waag DM
- Subjects
- Antibodies, Bacterial immunology, Bacillus anthracis chemistry, Burkholderia pseudomallei chemistry, Francisella tularensis chemistry, Antibodies, Bacterial analysis, Bacillus anthracis immunology, Burkholderia pseudomallei immunology, Carbohydrates chemistry, Francisella tularensis immunology, Microarray Analysis methods
- Abstract
We developed a microarray platform by immobilizing bacterial 'signature' carbohydrates onto epoxide modified glass slides. The carbohydrate microarray platform was probed with sera from non-melioidosis and melioidosis (Burkholderia pseudomallei) individuals. The platform was also probed with sera from rabbits vaccinated with Bacillus anthracis spores and Francisella tularensis bacteria. By employing this microarray platform, we were able to detect and differentiate B. pseudomallei, B. anthracis and F. tularensis antibodies in infected patients, and infected or vaccinated animals. These antibodies were absent in the sera of naïve test subjects. The advantages of the carbohydrate microarray technology over the traditional indirect hemagglutination and microagglutination tests for the serodiagnosis of melioidosis and tularemia are discussed. Furthermore, this array is a multiplex carbohydrate microarray for the detection of all three biothreat bacterial infections including melioidosis, anthrax and tularemia with one, multivalent device. The implication is that this technology could be expanded to include a wide array of infectious and biothreat agents.
- Published
- 2008
- Full Text
- View/download PDF
36. Synthesis of spacer-equipped di-, tri-, and the tetrasaccharide fragments of the deacetylated O-PS1 of Citrobacter gillenii O9a,9b, and a related pentasaccharide.
- Author
-
Saksena R, Chernyak A, and Kovác P
- Subjects
- Citrobacter chemistry, O Antigens chemistry, Oligosaccharides chemical synthesis
- Abstract
The title rhamnooligosaccharides [alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, alpha-D-Rhap4NAc-(1-->2)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe, and alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->2)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-(1-->3)-alpha-D-Rhap4NAc-1-O-(CH(2))(5)COOMe] were synthesized in a stepwise fashion from 5-methoxycarbonylpentyl 4-azido-4,6-dideoxy-2-O-benzyl-alpha-D-mannopyranoside and orthogonally protected 1-thioglycoside glycosyl donors. The amorphous, final products were fully characterized as corresponding per-O-acetyl derivatives.
- Published
- 2008
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37. Preparation of glycoconjugates by dialkyl squarate chemistry revisited.
- Author
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Hou SJ, Saksena R, and Kovác P
- Subjects
- Drug Stability, Hydrogen-Ion Concentration, Hydrolysis, Indicators and Reagents, Cyclobutanes chemistry, Glycoconjugates chemical synthesis
- Abstract
The methyl 6-hydroxyhexanoyl glycoside of lactose was treated with each of 1,2-diaminoethane or hydrazine hydrate, and the corresponding amino amide 4 and acyl hydrazide 13, were treated with each of squaric acid dimethyl, diethyl, dibutyl, and didecyl esters. The monoesters were conjugated to bovine serum albumin (BSA) at different concentrations of hapten using 0.05 and 0.5M pH 9 borate buffer. Maximum loading was achieved faster, and the conjugation efficiency was higher, when the conjugation was conducted at higher concentrations of both hapten and buffer. Conjugations involving haptens 14-17 prepared from hydrazide 13 were generally slower and less efficient than those with compounds 5-8, which were made from amino amide 4. Maintaining pH 9 during conjugation was found to be the most important factor in ensuring that the conjugation was a fast, highly efficient, and reproducible process. When the pH of the conjugation mixture fell during the reaction, resulting in decreased reaction rate or even termination of the conjugation process, the normal course of the conjugation process could be restored by addition of buffer salts. Hydrolysis studies with monoesters formed from amino amide 4 under conjugation conditions showed that decyl ester 8 was the most stable and that the methyl compound 5 was the one most readily hydrolyzed. The stability of monoesters prepared from hydrazide 13 was similar and comparable to the decyl ester prepared from 4. No definite advantage was found for the use of any of the four dialkyl squarate reagents (methyl-, ethyl-, butyl-, and decyl-) for conversion of carbohydrate derivatives to species amenable for conjugation. Nevertheless, dimethyl squarate seemed to be the most convenient reagent because it is a crystalline, easy to handle, and commercially available material with very good reactivity.
- Published
- 2008
- Full Text
- View/download PDF
38. Immunogens related to the synthetic tetrasaccharide side chain of the Bacillus anthracis exosporium.
- Author
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Saksena R, Adamo R, and Kovác P
- Subjects
- Bacillus anthracis physiology, Carbohydrate Conformation, Carbohydrate Sequence, Magnetic Resonance Spectroscopy, Molecular Sequence Data, Spectrometry, Mass, Fast Atom Bombardment, Bacillus anthracis chemistry, Bacterial Vaccines chemistry, Spores, Bacterial chemistry
- Abstract
The known methyl 2-O-acetyl-3,4-di-O-benzyl-1-thio-alpha-L-rhamnopyranoside (3) was converted to the corresponding 5-methoxycarbonylpentyl glycoside 4 which was deacetylated. The product 5 was used as the initial glycosyl acceptor to construct two trirhamnoside glycosyl acceptors having HO-3(III) flanked by either benzoyl or benzyl groups, compounds 10 and 29, respectively [fully protected, except HO-3(III), alpha-L-Rha-(1-->3)-alpha-L-Rha-(1-->2)-alpha-L-Rha-1-O-(CH2)5COOCH3]. When these were glycosylated with ethyl 4-azido-3-O-benzyl-4,6-dideoxy-2-O-bromoacetyl-1-thio-beta-D-glucopyranoside (18), only the benzylated glycosyl acceptor 29 gave good yield of the desired tetrasaccharide 30. The alpha- and beta-linked products, together with the corresponding orthoester 23, were formed in almost equal amount when glycosylation of 10 was performed with the glycosyl donor carrying the 2-O-bromoacetyl protecting group. Deprotection at O-2 of 30, followed by further functionalization of the molecule and global deprotection, gave the 5-methoxycarbonylpentyl glycoside of the title tetrasaccharide, beta-Ant-(1-->3)-alpha-L-Rha-(1-->3)-alpha-L-Rha-(1-->2)-alpha-L-Rha (35). Except for differences due to presence of the anomeric 5-methoxycarbonylpentyl group, the fully assigned NMR spectra of glycoside 35 were found to be virtually identical to those reported for the parent tetrasaccharide isolated from Bacillus anthracis exosporium, thus proving the correct structure assigned to the naturally occurring substance. All theoretically possible structural fragments of 35, as well as analog of 35 lacking the 2-O-methyl group at the terminal 4,6-dideoxyglucosyl residue, compound 40, were also synthesized. Tetrasaccharide 35, its beta-linked and non-methylated analogs 2 and 40, respectively, as well as the trirhamnoside fragment of 35, glycoside 12, were further functionalized and conjugated to BSA using squaric acid chemistry, to give neoglycoconjugates with a predetermined carbohydrate-protein ratio of approximately 3 and approximately 6.
- Published
- 2007
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39. Photogenerated glycan arrays identify immunogenic sugar moieties of Bacillus anthracis exosporium.
- Author
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Wang D, Carroll GT, Turro NJ, Koberstein JT, Kovác P, Saksena R, Adamo R, Herzenberg LA, Herzenberg LA, and Steinman L
- Subjects
- Animals, Antigens, Bacterial chemistry, Bacillus anthracis chemistry, Polysaccharides chemistry, Rabbits, Spores, Bacterial chemistry, Spores, Bacterial immunology, Antigens, Bacterial immunology, Bacillus anthracis immunology, Light, Microarray Analysis, Polysaccharides immunology
- Abstract
Using photogenerated glycan arrays, we characterized a large panel of synthetic carbohydrates for their antigenic reactivities with pathogen-specific antibodies. We discovered that rabbit IgG antibodies elicited by Bacillus anthracis spores specifically recognize a tetrasaccharide chain that decorates the outermost surfaces of the B. anthracis exosporium. Since this sugar moiety is highly specific for the spores of B. anthracis, it appears to be a key biomarker for detection of B. anthracis spores and development of novel vaccines that target anthrax spores.
- Published
- 2007
- Full Text
- View/download PDF
40. Immunogenicity of synthetic saccharide fragments of Vibrio cholerae O1 (Ogawa and Inaba) bound to Exotoxin A.
- Author
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Wade TK, Saksena R, Shiloach J, Kovác P, and Wade WF
- Subjects
- ADP Ribose Transferases chemistry, ADP Ribose Transferases pharmacology, Animals, Bacterial Toxins chemistry, Bacterial Toxins pharmacology, Carbohydrate Conformation, Carbohydrate Sequence, Cholera microbiology, Cholera prevention & control, Cholera virology, Cholera Vaccines chemistry, Cholera Vaccines pharmacology, Exotoxins chemistry, Exotoxins pharmacology, Female, Immunoconjugates chemistry, Immunoconjugates pharmacology, Immunoglobulin M immunology, Lipopolysaccharides immunology, Lipopolysaccharides pharmacology, Mice, Mice, Inbred BALB C, Molecular Sequence Data, Oligosaccharides chemistry, Vibrio cholerae O1 chemistry, Virulence Factors chemistry, Virulence Factors pharmacology, Pseudomonas aeruginosa Exotoxin A, ADP Ribose Transferases immunology, Bacterial Toxins immunology, Cholera immunology, Cholera Vaccines immunology, Exotoxins immunology, Immunoconjugates immunology, Oligosaccharides immunology, Vibrio cholerae O1 immunology, Virulence Factors immunology
- Abstract
Recombinant exotoxin A (rEPA) from Pseudomonas aeruginosa conjugated to Vibrio cholerae O1 serotype-specific polysaccharides (mono-, di- and hexasaccharide) were immunogenic in mice. Monosaccharide conjugates boosted the humoral responses to the hexasaccharide conjugates. Prior exposure to purified Ogawa lipopolysaccharide (LPS) enabled contra-serotype hexasaccharide conjugates to boost the vibriocidal response, but Inaba LPS did not prime for an enhanced vibriocidal response by a contra-serotype conjugate. Prior exposure to the carrier, and priming B cells with the LPS of either serotype, resulted in enhanced vibriocidal titers if the Ogawa hexasaccharides were used, but a diminished response to the Inaba LPS. These studies demonstrate that the 'functional' B cell epitopes on the LPS differ from those of the neoglycoconjugates and that the order of immunization and the serotype of the boosting conjugate can influence the epitope specificity and function of the antisera.
- Published
- 2006
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41. Length of the linker and the interval between immunizations influences the efficacy of Vibrio cholerae O1, Ogawa hexasaccharide neoglycoconjugates.
- Author
-
Saksena R, Ma X, Wade TK, Kovác P, and Wade WF
- Subjects
- Animals, Antibodies, Bacterial biosynthesis, Antibodies, Bacterial immunology, B-Lymphocytes immunology, Carbohydrate Sequence, Cholera Vaccines chemistry, Female, Immunoglobulin M biosynthesis, Immunoglobulin M immunology, Immunologic Memory, Lipopolysaccharides chemistry, Mice, Mice, Inbred BALB C, Molecular Sequence Data, O Antigens chemistry, Pregnancy, Serum Albumin, Bovine chemistry, Serum Albumin, Bovine immunology, Structure-Activity Relationship, Cholera Vaccines immunology, Lipopolysaccharides immunology, O Antigens immunology, Vibrio cholerae O1 immunology
- Abstract
Ogawa hexasaccharide neoglycoconjugates induce protective antibodies in mice. Similar Ogawa conjugates but with a longer linker that connects the carrier to shorter saccharides are immunogenic, but generally ineffective at inducing vibriocidal or protective antibodies. The efficacy of Ogawa hexasaccharide neoglycoconjugates of different linker lengths were tested. The majority of mice given immunizations separated by a 14-day gap did not produce vibriocidal or protective antibodies. Mice immunized 28 days apart with immunogens containing the shortest or medium length linker, but not the longest, produced vibriocidal and protective antibodies. A nonprotective, priming dose of purified Ogawa LPS followed 5 days later with a booster of the Ogawa neoglycoconjugates (di-, tetra-, or hexasaccharide) resulted in vibriocidal antibodies at day 10.
- Published
- 2006
- Full Text
- View/download PDF
42. Synthesis of the tetrasaccharide side chain of the major glycoprotein of the Bacillus anthracis exosporium.
- Author
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Saksena R, Adamo R, and Kovác P
- Subjects
- Carbohydrate Conformation, Carbohydrate Sequence, Magnetic Resonance Spectroscopy, Molecular Sequence Data, Oligosaccharides isolation & purification, Anti-Bacterial Agents pharmacology, Bacillus anthracis chemistry, Bacterial Proteins chemistry, Glycoproteins chemical synthesis, Oligosaccharides chemical synthesis
- Abstract
An alpha-glycoside of the tetrasaccharide sequence beta-Ant-(1-->3)-alpha-l-Rhap-(1-->3)-alpha-l-Rhap-(1-->2)-alpha-l-Rhap whose aglycon allows conjugation to suitable carriers was synthesized. The NMR characteristics of the compound are virtually identical with those of the alpha-anomer of the tetrasaccharide isolated from the major glycoprotein of the Bacillus anthracis exosporium. Thus, the correct structure of the natural product has been proven by chemical synthesis.
- Published
- 2006
- Full Text
- View/download PDF
43. Synthesis of the beta anomer of the spacer-equipped tetrasaccharide side chain of the major glycoprotein of the Bacillus anthracis exosporium.
- Author
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Adamo R, Saksena R, and Kovác P
- Subjects
- Carbohydrate Conformation, Carbohydrate Sequence, Membrane Glycoproteins chemistry, Models, Molecular, Molecular Sequence Data, Oligosaccharides chemistry, Bacillus anthracis metabolism, Membrane Glycoproteins biosynthesis, Oligosaccharides biosynthesis
- Abstract
The beta glycoside of the tetrasaccharide sequence beta-Ant-(1-->3)-alpha-l-Rhap-(1-->3)-alpha-l-Rhap-(1-->2)-l-Rhap, whose aglycon allows conjugation to proteins, was synthesized for the first time. A stepwise synthetic approach was applied with thioglycosides as glycosyl donors, and the beta anomer of the compound was obtained equipped with a spacer group whose further transformation allows conjugation to suitable carriers. To synthesize the beta-anthrosyl linkage with high stereoselectivity, a linker-equipped rhamnotriose derivative was glycosylated with ethyl 4-azido-3-O-benzyl-2-O-bromoacetyl-4,6-dideoxy-1-thio-beta-d-glucopyranoside. Further functionalization of the tetrasaccharide thus obtained, followed by deprotection, gave the target substance.
- Published
- 2005
- Full Text
- View/download PDF
44. Effect of saccharide length on the immunogenicity of neoglycoconjugates from synthetic fragments of the O-SP of Vibrio cholerae O1, serotype Ogawa.
- Author
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Saksena R, Ma X, Wade TK, Kovác P, and Wade WF
- Subjects
- Animals, Antibodies, Bacterial biosynthesis, Antibodies, Bacterial blood, Dose-Response Relationship, Immunologic, Female, Glycoconjugates immunology, Immunoglobulin M biosynthesis, Immunoglobulin M blood, Lipopolysaccharides immunology, Mice, Mice, Inbred BALB C, O Antigens chemistry, Peptide Fragments chemistry, Serotyping, O Antigens immunology, Peptide Fragments immunology, Vibrio cholerae O1 classification, Vibrio cholerae O1 immunology
- Abstract
A synthetic hexasaccharide, identical to the terminal hexasaccharide of Ogawa LPS, coupled to bovine serum albumin induced protective antibodies in mice. To determine if there was a minimum saccharide length required for immunogenicity and efficacy, shorter (mono- to pentasaccharide) neoglycoconjugates (CHO-BSA) were tested in mice. The Ogawa CHO-BSA was inoculated at either a constant mass but differing moles, or equal moles but differing masses. Humoral responses were essentially the same when mice received 9 microg of the carbohydrate (0.007 mM with the pentasaccharide) in each of the neoglycoconjugates prepared from mono- through the pentasaccharide, or the same molar amount (0.007 mM), proportionally less by weight when going from the penta- to the monosaccharide. These data show that, within this dose range, the responses occurred virtually independently of the amount of immunogen. Humoral antibodies induced by these immunogens were generally not vibriocidal. Selected antisera induced by CHO-BSA immunogens were protective, but the ELISA titers of the sera were not predictive of the protective capacity. Purified, Ogawa LPS induced anti-Ogawa LPS IgM antibody titers similar to those induced by the Ogawa CHO-BSA conjugates. The anti-whole LPS sera were strongly vibriocidal, as were the previously reported sera induced by hexasaccharide conjugates. This suggests either that the shorter oligosaccharides lack a conformational epitope provided by the hexasaccharide or that the LPS has additional B cell epitopes or selects different B cells in the primary response.
- Published
- 2005
- Full Text
- View/download PDF
45. Studies toward a conjugate vaccine for anthrax. Synthesis and characterization of anthrose [4,6-dideoxy-4-(3-hydroxy-3-methylbutanamido)-2-O-methyl-D-glucopyranose] and its methyl glycosides.
- Author
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Saksena R, Adamo R, and Kovác P
- Subjects
- Amino Sugars chemical synthesis, Anthrax Vaccines chemical synthesis, Carbohydrate Sequence, Deoxyglucose chemical synthesis, Deoxyglucose chemistry, Glucosides chemical synthesis, Molecular Sequence Data, Vaccines, Conjugate chemistry, Amino Sugars chemistry, Anthrax Vaccines chemistry, Deoxyglucose analogs & derivatives, Glucosides chemistry
- Abstract
The key step in the first chemical synthesis of anthrose (16) and its methyl alpha- (6) and beta-glycoside (22) was inversion of configuration at C-2 in triflates 10, 2, and 18, respectively, obtained from the common intermediate, methyl 4-azido-3-O-benzyl-4,6-dideoxy-alpha-D-mannopyranoside (1). To prepare methyl alpha-anthroside (6), methylation at O-2 of the gluco product 3, obtained from 2, was followed by hydrogenation/hydrogenolysis of the formed 2-methyl ether 4, to simultaneously remove the protecting benzyl group and reduce the azido function. Subsequent N-acylation of the formed amine 5 with 3-hydroxy-3-methylbutyric acid gave the target methyl alpha-glycoside 6. Synthesis of methyl beta-anthroside (22) comprised the same sequence of reactions, starting from the known methyl 4-azido-3-O-benzyl-4,6-dideoxy-beta-D-mannopyranoside (17), which was prepared from 1. In the synthesis of anthrose (16), 1-thio-beta-glucoside 11, obtained from 1 through 10, was methylated at O-2, and the azido function in the resulting benzylated 1-thioglycoside 12 was selectively reduced to give amine 13. After N-acylation with 3-hydroxy-3-methylbutyric acid, 1-thioglycoside 14 was hydrolyzed to give the corresponding reducing sugar, aldol 15, which was debenzylated to afford anthrose.
- Published
- 2005
- Full Text
- View/download PDF
46. Synthetic fragments of Vibrio cholerae O1 Inaba O-specific polysaccharide bound to a protein carrier are immunogenic in mice but do not induce protective antibodies.
- Author
-
Meeks MD, Saksena R, Ma X, Wade TK, Taylor RK, Kovác P, and Wade WF
- Subjects
- Animals, Female, Mice, O Antigens metabolism, Serum Albumin, Bovine metabolism, Antibodies immunology, O Antigens immunology, Vibrio cholerae O1 immunology
- Abstract
Development of Vibrio cholerae lipopolysaccharide (LPS) as a cholera vaccine immunogen is justified by the correlation of vibriocidal anti-LPS response with immunity. Two V. cholerae O1 LPS serotypes, Inaba and Ogawa, are associated with endemic and pandemic cholera. Both serotypes induce protective antibody following infection or vaccination. Structurally, the LPSs that define the serotypes are identical except for the terminal perosamine moiety, which has a methoxyl group at position 2 in Ogawa but a hydroxyl group in Inaba. The terminal sugar of the Ogawa LPS is a protective B-cell epitope. We chemically synthesized the terminal hexasaccharides of V. cholerae serotype Ogawa, which comprises in part the O-specific polysaccharide component of the native LPS, and coupled the oligosaccharide at different molar ratios to bovine serum albumin (BSA). Our initial studies with Ogawa immunogens showed that the conjugates induced protective antibody. We hypothesized that antibodies specific for the terminal sugar of Inaba LPS would also be protective. Neoglycoconjugates were prepared from synthetic Inaba oligosaccharides (disaccharide, tetrasaccharide, and hexasaccharide) and BSA at different levels of substitution. BALB/c mice responded to the Inaba carbohydrate (CHO)-BSA conjugates with levels of serum antibodies of comparable magnitude to those of mice immunized with Ogawa CHO-BSA conjugates, but the Inaba-specific antibodies (immunoglobulin M [IgM] and IgG1) were neither vibriocidal nor protective in the infant mouse cholera model. We hypothesize that the anti-Inaba antibodies induced by the Inaba CHO-BSA conjugates have enough affinity to be screened via enzyme-linked immunosorbent assay but not enough to be protective in vivo.
- Published
- 2004
- Full Text
- View/download PDF
47. One-pot preparation of a series of glycoconjugates with predetermined antigen-carrier ratio from oligosaccharides that mimic the O-PS of Vibrio cholerae O:1, serotype Ogawa.
- Author
-
Saksena R, Ma X, and Kovác P
- Subjects
- Amines chemistry, Carbohydrate Conformation, Carbohydrate Sequence, Glycoconjugates chemistry, Glycosides chemistry, Haptens chemistry, Molecular Sequence Data, Oligosaccharides chemistry, Polysaccharides chemistry, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Time Factors, Antigens chemistry, Glycoconjugates chemical synthesis, Oligosaccharides chemical synthesis, Polysaccharides, Bacterial chemistry, Vibrio cholerae metabolism
- Abstract
Di-through the pentasaccharide that mimic the upstream terminus of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Ogawa were synthesized in the form of 5-methoxycarbonylpentyl glycosides and linked to BSA using squaric acid diester chemistry. The conjugation reactions were monitored by surface-enhanced laser-desorption/ionization-time-of-flight mass spectrometry (SELDI-TOF MS), which allowed conducting the conjugation of the synthetic oligosaccharides in a controlled way and termination of the reaction when the desired molar hapten-BSA ratio had been reached. This made it possible to prepare, from one hapten in a one-pot reaction, a series of neoglycoconjugates having different, predetermined carbohydrate-carrier ratios. The accuracy of molecular mass determination in SELDI-TOF MS analysis could be increased by using the carrier protein as the internal standard.
- Published
- 2003
- Full Text
- View/download PDF
48. Neoglycoconjugates from synthetic tetra- and hexasaccharides that mimic the terminus of the O-PS of Vibrio cholerae O:1, serotype Inaba.
- Author
-
Ma X, Saksena R, Chernyak A, and Kovác P
- Subjects
- Carbohydrate Sequence, Magnetic Resonance Spectroscopy, Mass Spectrometry, Molecular Sequence Data, Glycoconjugates chemistry, Oligosaccharides chemistry, Vibrio cholerae chemistry
- Abstract
A glycosyl acceptor and a glycosyl donor having the N-3-deoxy-L-glycero-tetronic acid side chain already attached have been prepared and used for the synthesis of the di-through to the hexasaccharide that mimic the upsteam terminus of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Inaba. The target tetra- and the hexasaccharide, which were obtained in the form of 5-methoxycarbonylpentyl glycosides, were linked to BSA using squaric acid diester chemistry. The conjugation reactions were monitored by surface enhanced laser desorption ionization-time of flight mass spectrometry (SELDI-TOF MS). This allowed the progression of the conjugation of the synthetic oligosaccharides in a controlled way and termination of the reaction when the desired molar hapten/BSA ratio had been reached, yielding neoglycoconjugates with predetermined carbohydrate/carrier ratios. The ability to monitor the conjugation by the SELDI-TOF MS technique made it possible to prepare, from one hapten in a one-pot reaction, several neoglycoconjugates having different, predetermined carbohydrate/carrier ratios.
- Published
- 2003
- Full Text
- View/download PDF
49. Conjugating low molecular mass carbohydrates to proteins. 2. Recovery of excess ligand used in the conjugation reaction.
- Author
-
Saksena R, Chernyak A, Poirot E, and Kovác P
- Subjects
- Carbohydrate Sequence, Ligands, Molecular Sequence Data, Molecular Weight, Nuclear Magnetic Resonance, Biomolecular, Spectrometry, Mass, Fast Atom Bombardment, Vibrio cholerae chemistry, Carbohydrates chemistry, Proteins chemistry
- Published
- 2003
- Full Text
- View/download PDF
50. Conjugating low molecular mass carbohydrates to proteins. 1. Monitoring the progress of conjugation.
- Author
-
Saksena R, Chernyak A, Karavanov A, and Kovác P
- Subjects
- Carbohydrate Conformation, Carbohydrate Sequence, Molecular Sequence Data, Molecular Weight, Carbohydrates chemistry, Proteins chemistry
- Published
- 2003
- Full Text
- View/download PDF
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