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Sahu S, Mohanty I, Narasimham MV, Pasupalak S, Parida B. Primary meningococcal arthritis of sacroiliac joint: a rare case report. Indian J Med Microbiol 2013; 31:87-9. [PMID: 23508440 DOI: 10.4103/0255-0857.108743] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Infection of the sacroiliac joint is a rare entity. Clinical signs and symptoms are usually nonspecific and result in delayed diagnosis. We report a rare case of primary meningococcal arthritis of right sacroiliac joint in an 11-year-old male child. Synovial fluid aspirated from the joint space showed Gram-negative diplococci which were confirmed as Neisseria meningitidis by culture and necessary biochemical tests followed by serogrouping by using polyvalent antisera. He was treated successfully with antibiotics.
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Bhatia K, Lakshmi, Serah, Shakeela, Yadav R, Sahu S, Mathai KI. A six month audit of workload and outcomes of dept of neurosurgery in a tertiary care institute. JOURNAL OF MARINE MEDICAL SOCIETY 2013. [DOI: 10.4103/0975-3605.203314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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78
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Sudhakar N, Samanta S, Sahu S, Raina O, Gupta SC, Madhu D, Kumar A. Prevalence of Toxocara species eggs in soil samples of public health importance in and around Bareilly, Uttar Pradesh, India. Vet World 2013. [DOI: 10.5455/vetworld.2013.87-90] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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79
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Mallick P, Sahu S. Structure, Microstructure and Optical Absorption Analysis of CuO Nanoparticles Synthesized by Sol-Gel Route. ACTA ACUST UNITED AC 2012. [DOI: 10.5923/j.nn.20120203.05] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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80
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Rosenthal VD, Todi SK, Álvarez-Moreno C, Pawar M, Karlekar A, Zeggwagh AA, Mitrev Z, Udwadia FE, Navoa-Ng JA, Chakravarthy M, Salomao R, Sahu S, Dilek A, Kanj SS, Guanche-Garcell H, Cuéllar LE, Ersoz G, Nevzat-Yalcin A, Jaggi N, Medeiros EA, Ye G, Akan ÖA, Mapp T, Castañeda-Sabogal A, Matta-Cortés L, Sirmatel F, Olarte N, Torres-Hernández H, Barahona-Guzmán N, Fernández-Hidalgo R, Villamil-Gómez W, Sztokhamer D, Forciniti S, Berba R, Turgut H, Bin C, Yang Y, Pérez-Serrato I, Lastra CE, Singh S, Ozdemir D, Ulusoy S. Impact of a multidimensional infection control strategy on catheter-associated urinary tract infection rates in the adult intensive care units of 15 developing countries: findings of the International Nosocomial Infection Control Consortium (INICC). Infection 2012; 40:517-26. [DOI: 10.1007/s15010-012-0278-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 05/25/2012] [Indexed: 11/24/2022]
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81
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Jena M, Malakar D, De A, Garg S, Akshey Y, Dutta R, Sahu S, Mohanty A, Kaushik J. Handmade cloned and parthenogenetic goat embryos – A comparison of different culture media and donor cells. Small Rumin Res 2012. [DOI: 10.1016/j.smallrumres.2012.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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82
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Garg S, Dutta R, Malakar D, Jena M, Kumar D, Sahu S, Prakash B. Cardiomyocytes rhythmically beating generated from goat embryonic stem cell. Theriogenology 2012; 77:829-39. [DOI: 10.1016/j.theriogenology.2011.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Revised: 05/10/2011] [Accepted: 05/13/2011] [Indexed: 12/18/2022]
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83
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Gokhale A, Kumar N, Sudhakar B, Sahu S, Basumatary H, Dhara S. Cellular Metals and Ceramics for Defence Applications. DEFENCE SCI J 2011. [DOI: 10.14429/dsj.61.640] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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84
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Anilkumar P, Lu F, Cao L, Luo PG, Liu JH, Sahu S, Tackett KN, Wang Y, Sun YP. Fullerenes for applications in biology and medicine. Curr Med Chem 2011; 18:2045-59. [PMID: 21517770 DOI: 10.2174/092986711795656225] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 04/05/2011] [Indexed: 11/22/2022]
Abstract
Fullerenes as a unique class of carbon allotropes have been studied extensively for their distinctive material properties and potential technological applications, including those in biology and medicine. Since a major focus in the latter has been on drug development and formulation, in this paper we highlight some representative studies related to such a focus, including the use of fullerenes for drug-like functions and for their improving the formulation of established drugs. Also discussed are some other potential medically relevant applications of fullerenes, such as their serving as potent agents in photodynamic therapy and magnetic imaging.
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Alam A, Sahu S. Magnetic Resonance Imaging in Evaluation of Periventricular Leukomalacia. Med J Armed Forces India 2011; 66:374-80. [PMID: 27365746 DOI: 10.1016/s0377-1237(10)80022-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 06/07/2010] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Improvements in perinatal care have resulted in increased survival of infants born prematurely, however neurological damage due to ischaemic infarction of the periventricular white matter is a problem of enormous medical, social and economic importance. Such vascular insult leads to destruction of the periventricular white matter, termed periventricular leukomalacia (PVL). This abnormality is the leading cause of significant morbidity in the survivors of premature birth. Magnetic Resonance Imaging (MRI) is perhaps the only imaging modality, which can accurately detect and quantify periventricular leukomalacia. METHODS Magnetic Resonance Imaging was carried out in 45 children in the age group of 4 weeks to 8 years, with history of premature birth and perinatal hypoxia. These children had neurological deficits ranging from cortical blindness, spastic diplegia, spastic quadriplegia to severe mental retardation. The procedure was carried out on a 1.5 Tesla (Siemens Magnetom Avanto) MR system using available protocols for imaging the paediatric brain. RESULT The study revealed that MR imaging could accurately identify areas of ischaemic infarction of the periventricular white matter both in the early as well as in the late stages. The pattern of abnormalities detected on MRI of the brain in these patients can be considered specific for PVL in the clinical background of premature birth and perinatal hypoxia. CONCLUSION MRI is the ideal imaging modality to detect, quantify and accurately map the areas of brain affected by this hypoxic-ischaemic process. It is presently the gold standard for evaluating the neuroparenchyma in those with perinatal hypoxia. Advanced MR techniques like Diffusion Weighted Imaging (DWI), Proton MR Spectroscopy and DTI have shown great promise in our understanding of the pathophysiology and anatomic considerations of this disease process.
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Alam A, Sahu S, Indrajit IK, Sahani H, Bhatia M, Kumar R. Gastroschisis-antenatal diagnosis. Med J Armed Forces India 2011; 67:169-70. [PMID: 27365793 DOI: 10.1016/s0377-1237(11)60026-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 06/06/2010] [Indexed: 10/18/2022] Open
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87
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Sahu S, Muthuvel S, Naware SS, Dhavala SS. Congenital Cystic Adenomatoid Malformation of Lung. Med J Armed Forces India 2011; 64:268-9. [PMID: 27408162 DOI: 10.1016/s0377-1237(08)80113-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 06/22/2007] [Indexed: 11/18/2022] Open
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88
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Alam A, Sree Ram MN, Sahu S. Lipoma of the Corpus Callosum : Diagnosis Using Magnetic Resonance Imaging. Med J Armed Forces India 2011; 62:299-300. [PMID: 27407919 DOI: 10.1016/s0377-1237(06)80032-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Accepted: 03/28/2005] [Indexed: 11/27/2022] Open
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89
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Sahu S, Kavuri NC, Kundu M. Dissolution kinetics of nickel laterite ore using different secondary metabolic acids. BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING 2011. [DOI: 10.1590/s0104-66322011000200009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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90
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Sahu S, Kumar A, Sen A. Macrodystrophia lipomatosa. Med J Armed Forces India 2011; 67:162-4. [PMID: 27365790 DOI: 10.1016/s0377-1237(11)60022-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2009] [Accepted: 07/10/2010] [Indexed: 10/18/2022] Open
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91
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Saha D, Sahu S, Chandra PC. Arsenic-safe alternate aquifers and their hydraulic characteristics in contaminated areas of Middle Ganga Plain, Eastern India. ENVIRONMENTAL MONITORING AND ASSESSMENT 2011; 175:331-348. [PMID: 20563899 DOI: 10.1007/s10661-010-1535-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 05/26/2010] [Indexed: 05/29/2023]
Abstract
Arsenic groundwater contamination exceeding 0.05 mg/l affecting the Newer Alluvial tracts of Patna and Bhojpur, the two worst affected districts located in the Middle Ganga Plain in the Bihar state, has been studied The area is underlain by two-tier Quaternary aquifer systems within a depth of 300 m below ground level, separated by a 15-32-m-thick clay/sandy clay aquitard. The upper part (<50 m depth) of the shallow aquifer system is arsenic-contaminated. The deeper aquifer system (lying below 120-130 m depth) exhibits low arsenic load (max 0.0035 mg/l), having hydraulic conductivity between 64.88 and 82.04 m/day. Groundwater in the deeper aquifer occurs under semi-confined to confined condition due to poor hydraulic conductivity of the middle clay (4.7×10(-2)-7.2×10(-3) m/day). Hydraulic head of the deeper aquifer remains close to the surface than the shallow aquifer. The two aquifer systems in the Newer Alluvium are replaced by a thick single aquifer system in the adjoining Older Alluvium, within a depth of 330 m below ground. In the arsenic-contaminated area, deeper aquifer is protected by a middle clay, which may be developed for community drinking water supply by deep tube wells having a yield capacity of 150 m3/h.
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De A, Malakar D, Akshey Y, Jena M, Garg S, Dutta R, Sahu S. In vitro development of goat (Capra hircus) embryos following cysteamine supplementation of the in vitro maturation and in vitro culture media. Small Rumin Res 2011. [DOI: 10.1016/j.smallrumres.2011.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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93
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Goodchild M, Sahu S, Wares F, Dewan P, Shukla RS, Chauhan LS, Floyd K. A cost-benefit analysis of scaling up tuberculosis control in India. Int J Tuberc Lung Dis 2011; 15:358-362. [PMID: 21333103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
OBJECTIVES To measure the economic costs and benefits of scaling up tuberculosis (TB) control under the Revised National Tuberculosis Control Programme (RNTCP) in India. DESIGN Modelling based on country-level programme and epidemiological data from 1997 to 2006. RESULTS The scale-up of TB control in India has resulted in a total health benefit of 29.2 million disability-adjusted life years (DALYs), including 1.3 million deaths averted. In 2006, the burden of TB measured in terms of DALYs lost would have been 1.8 times higher in the absence of the programme. The total gain in economic well-being from TB control is estimated at US$88.1 billion over the 1997-2006 10-year period. Total public expenditure on TB control over this period amounted to US$768 million, with the RNTCP accounting for US$299 million and other health sector costs accounting for US$469 million. The cost of TB control averaged just US$26 per DALY gained over 1997-2006 and generated a return of US$115 per dollar spent. CONCLUSIONS The scale-up of TB control has been a very cost-effective strategy for improving the health status of India's population, while the return on investment has been exceptional from a societal perspective.
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Sharma SK, Panda BN, Mahapatra SS, Sahu S. Analysis of Barriers for Reverse Logistics: An Indian Perspective. ACTA ACUST UNITED AC 2011. [DOI: 10.7763/ijmo.2011.v1.18] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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95
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Garg S, Malakar D, Dutta R, Jena MK, De AK, Kumar D, Sahu S. 304 RHYTHMIC BEATING OF HEART MUSCLE GENERATED FROM GOAT EMBRYONIC STEM CELLS. Reprod Fertil Dev 2011. [DOI: 10.1071/rdv23n1ab304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The aim of the present study was to isolate, culture, and characterise goat embryonic stem cell (ESC)-like cells from in vitro fertilized goat embryos. Oocytes were collected from slaughterhouse goat ovaries, and IVF was performed with standard protocol. A total of 60.48% cleavage, 24.01% morulae, 11.35% blastocyst, and 3.4% hatched blastocyst were obtained. Goat ESC-like cells were isolated from individual blastomere cells of early embryos after 2 mg mL–1 of pronase treatment and inner cell mass (ICM) of blastocyst. The ICM were isolated mechanically from 80 expanded blastocysts and 20 hatched blastocysts and enzymatically from 45 expanded blastocysts and 20 hatched blastocysts. The primary colony formation was obtained mechanically from expanded blastocysts (66%) and hatched blastocysts (90%) and enzymatically from expanded blastocysts (30%) and hatched blastocysts (73%). The ICM were cultured on 10 μg mL–1 of mitomycin-C inactivated fetal fibroblast feeder layer and with leukemia inhibitory factor (LIF) without feeder layer. Embryonic stem cells were cultured and characterised by immunofluorescence of surface markers such as alkaline phosphatase, Oct-4, SSEA-1, SSEA-3, SSEA-4 and intracellular molecular markers Oct-4, Sox2, Nanog. The primary colony formation was significantly higher when hatched blastocysts (90%) were used for ICM than when expanded blastocysts (66%), morulae (15%), and single blastomere (10%) were used. Five goat ESC lines were produced, which were maintained undifferentiated on a feeder layer in ESC medium containing LIF up to 5th, 7th, 10th, 20th, and 22nd passages. Three goat ESC lines were also produced in ESC medium containing LIF without feeder layer and maintained undifferentiated up to 5th, 10th, and 12th passages. All the cell lines expressed alkaline phophatase and OCT-4, at 5th, 10th, 15th, and 20th passages. The ESC of passage 20 were used for embryoid body formation for 3 days. The embryoid bodies were cultured to induce differentiation in medium contain activin-A, fibroblast growth factor-2, and BMP-4. The embryoid bodies were analysed with molecular markers such as Gata, BMP4, and Nestin and were found positive. The cardiac tissues were also observed to be positive with cardiac-specific molecular markers such as α actinin, troponin, and α-myosin heavy chain and its histology. The rhythmic beating was found after 30 days of culture, and the beating was still continuing after 42 days. These goat ESC were cryopreserved into LN2 for a long period of time for further use in the future. It could be concluded that goat ESC were maintained undifferentiated up to 22nd passage with feeder layer and 12th passages without feeder layer using LIF only. Cardiomyocyte rhythmic beating of heart muscle was generated from goat ESC. To the best of our knowledge, this is the first time beating has been observed in goat ESC cardiomyocytes in the world. The authors have not found any report on animals such as cattle, buffalo, sheep, and pig, except mouse, monkey, and human being.
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Kumar D, Malakar D, Dutta R, Garg S, Sahu S, Kaushik JK, Mohanty AK. 305 CONSTRUCTION OF TRANSCRIPTION FACTOR GENES FOR REPROGRAMMING OF ADULT GOAT FIBROBLAST CELLS FOR PRODUCTION OF INDUCED PLURIPOTENT STEM CELLS. Reprod Fertil Dev 2011. [DOI: 10.1071/rdv23n1ab305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Embryonic stem cells (ESC) are derived from the inner cell mass of blastocysts and proliferate extensively while maintaining pluripotency. They can be used for the treatment of juvenile diabetes, Parkinson’s disease, heart failure, and spinal cord injury. However, the use of embryos and tissue rejection remain concerns for ESC transplantation. Reprogramming of somatic cells may be done by different methods such as somatic cell nuclear transfer (Wilmut et al. 1997), fusion of somatic cells (Cowen et al. 2005), treatment with the extract of the pluripotent stem cells (Johnson Rajasingh 2008), and by the stable ectopic expression of defined factors in the somatic cells (Takahashi and Yamanaka 2006). Several transcription factors, including Oct3/4 (Nichols et al. 1998; Niwa et al. 2000), Sox2 (Avilion et al. 2003), and Nanog (Chambers et al. 2003; Mitsui et al. 2003), function in the maintenance of pluripotency in both early embryos and ESC. Takahashi and Yamanaka reported reprogramming the fibroblast cells into stem cells by introducing Oct3/4, Sox2, c-Myc, and Klf4 in mouse embryonic and adult fibroblasts. Yu et al. (2007) demonstrated that four transcription factors (OCT-4, SOX2, NANOG, and LIN28) are sufficient to reprogramme human somatic cells to pluripotent stem cells that exhibit the essential characteristics of ESC. Nakagawa et al. (2008) used three factors (OCT3/4, SOX2, and KLF4) for human iPS cell production from somatic cells. We are trying to reprogramme the adult goat fibroblast cells in induced pluripotent stem cells by using ectopic expression of transcription factors such as Oct-4, Sox2, Nanog, and Lin28. We collected the ovaries from a slaughtered animal from Delhi and collected the oocytes from ovaries. Then after the collection, A and B grade oocytes were selected. Selected oocytes were processed and incubated in in vitro maturation media for 24 h. We collected semen from a male goat, and it was processed and capacitated in sperm TALP. Capacitated sperms were used for IVF of the in vitro matured oocytes in ferTALP. After 12 h sperm were washed from oocytes in embryo developing media (EDM), and oocytes were cultured (in vitro) in EDM. After 24 h cleavage occurred. The cleaved embryos were cultured for 6 to 7 days. At the 7th day, we got blastocysts. From these blastocysts, inner cell mass was isolated enzymatically and cultured to get ESC. The ESC were cultured for 7 passages and used for RNA isolation. The RNA was isolated from these stem cells by the Trizol method. Complementary DNA was prepared by RT-PCR. Using gene-specific primer for Oct-4, Nanog, and Sox2, DNA was amplified. The DNA for the Oct-4, Nanog, and Sox2 genes was cloned in pJET cloning vector and transformed in Top10 E. coli competence cells. After screening, plasmid was isolated and sent for sequencing. Sequences were analysed and the complete open reading frame was created for Oct-4, Nanog, and Sox2.
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Lal SS, Sahu S, Wares F, Lönnroth K, Chauhan LS, Uplekar M. Intensified scale-up of public-private mix: a systems approach to tuberculosis care and control in India. Int J Tuberc Lung Dis 2011; 15:97-104. [PMID: 21276304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
SETTING India's Revised National Tuberculosis Control Programme (RNTCP) implemented an intensified scale-up of public-private mix (PPM) DOTS covering 50 million population in 14 major cities. OBJECTIVES To describe the processes and outcomes of the systems approach adopted. METHODS National schemes for engagement with different providers were applied. Additional human resources were provided to assist with implementation. All health care providers were mapped, a concise training module and advocacy kit were developed, and sensitisation and training activities were conducted. National advocacy efforts complemented local initiatives. Data were captured in a PPM-focused surveillance system. RESULTS Intensified PPM resulted in a 12% increase in notification of new smear-positive pulmonary TB cases. Contribution to case notification by providers varied widely: health department 67%, medical colleges 16%, private practitioners 6%, non-government organisations 7%, and the rest 4%. Treatment success was above the 85% target for all sectors combined. Strong public sector implementation and differentiation of roles and responsibilities among providers played major roles. The lessons learnt have been used by the RNTCP to inform future policy development. CONCLUSION The systems approach to the intensified PPM scale-up used in the 14 cities was productive. However, many challenges and barriers to scale-up of PPM DOTS in India remain.
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Akshey YS, Malakar D, De AK, Jena MK, Sahu S, Dutta R. Study of the Efficiency of Chemically Assisted Enucleation Method for Handmade Cloning in Goat (Capra hircus). Reprod Domest Anim 2010; 46:699-704. [DOI: 10.1111/j.1439-0531.2010.01732.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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99
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Nanda S, Sahu S, Abraham J. Studies on the biodegradation of natural and synthetic polyethylene by Pseudomonas spp. ACTA ACUST UNITED AC 2010. [DOI: 10.4314/jasem.v14i2.57839] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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100
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Ke B, Hawkridge FM, Sahu S. Redox titration of fluorescence yield of photosystem II. Proc Natl Acad Sci U S A 2010; 73:2211-5. [PMID: 16592332 PMCID: PMC430500 DOI: 10.1073/pnas.73.7.2211] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The variable fluorescence yield of photosystem II is dependent on the redox state of the fluorescence quencher molecule or the primary electron acceptor of the system. We have carried out redox titrations of fluorescence yield of a photochemically active photosystem-II reaction-center particle and have measured the redox potential of the photosystem-II primary acceptor.During reductive titrations using dithionite as the reductant, only a single quenching transition was observed. For instance, at pH 7.0, the midpoint potential of the fluorescence transition is -325 mV, and those at a pH between 6.0 and 7.5 are consistent with a pH dependence of about 60 mV/pH unit. At a given pH, the midpoint potential of the transition closely corresponds to that of the most negative transition previously measured in unfractionated chloroplasts (both by chemical reductive titration). Oxidative titrations using ferricyanide as the oxidant yielded hysteresis in the titration curves.Similar changes in fluorescence yield were observed in redox titrations by electrochemical reduction or oxidation. Electrochemical reductive and oxidative titrations yielded reversible transitions, contrary to the hysteresis observed during chemical oxidative titration. From coulometric-titration data, we have estimated that most likely one electron is involved in the redox transition of the fluorescence-quencher or primary-electron-acceptor molecule of photosystem II. These findings are consistent with the current proposal that a membrane-bound plastoquinone functions as the primary acceptor of photosystem II.
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