Publications by authors named "Parikshit Tyagi"

Yellow fever vaccine associated neurovirulence and viscerotropism have been reported by various countries. In this study, the neurovirulence, viscerotropism and immunogenicity of yellow fever vaccine seed lots (master and working) and final product manufactured at Serum Institute of India (SII) were evaluated in cynomolgus monkeys. WHO reference virus 168-73 and Stamarilâ„¢ as a control vaccine was used for comparison.

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Yellow fever, a mosquito-borne flavivirus infection, is an important public health problem in Africa and Latin America. A Yellow Fever vaccine (YFV) was developed and tested in a study in India. This was a Phase I, open-label, randomized, controlled study where healthy adults received SII YFV intramuscularly (SII YFV IM), SII YFV subcutaneously (SII YFV SC) or STAMARIL (Sanofi-Pasteur) in 1:1:1 ratio.

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Cell culture based live attenuated influenza vaccines (LAIV) as an alternative to egg-based LAIV have been explored because of lack of easy access to SPF eggs for large scale production. In this study, feasibility of MDCK platform was assessed by including multiple LAIV strains covering both type A (H1 and H3) and type B seasonal strains as well as the candidate pandemic potential strains like A/H5 and A/H7 for the growth in MDCK cells. A risk assessment study was conducted on the cell banks to evaluate safety concerns related to tumorigenicity with a regulatory perspective.

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During a pandemic, the availability of specific pathogen free chicken eggs is a major bottleneck for up-scaling response to the demand for influenza vaccine. This has led us to explore the use of Madin-Darby Canine Kidney (MDCK) cells for the manufacture of live attenuated influenza vaccine (LAIV) that provides production flexibility and speed. The present study reports the comparison of the immunogenicity and efficacy of two MDCK-based LAIVs against two egg-based LAIVs prepared from the same pandemic potential strains of H5 and H7 subtypes after a single dose of the vaccine followed by a challenge with a homologous wild type strain.

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A ferret challenge study was conducted to address the efficacy of the egg-based and Madin-Darby canine kidney (MDCK)-based live attenuated influenza vaccine (LAIV) strains. Vaccines derived as 6:2 reassortants from the A/Leningrad/134/17/57 master donor strain and the HA and NA components from the A/California/07/2009 (A/Cal)- and A/Michigan/45/2015 (A/Mich)-like strains of type A H1N1 influenza virus were used in the study. Monovalent, trivalent and quadrivalent formulations of the LAIV containing either of the two H1N1 strains were analysed.

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In the event of a highly pathogenic influenza pandemic, the Indian subcontinent would need 1.2 billion doses of vaccine to immunize its entire population, double if two doses were required to assure immunity. Serum Institute of India Limited (SII) thus became one of six initial grantees of the World Health Organization (WHO) technology transfer initiative to create capacity in developing countries to manufacture H5N1 pandemic influenza vaccine.

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A novel series of complexes of the type [M(TML)X2]; where TML is Tetradentate Macrocyclic Ligand; M = Co(II), Ni(II), Cu(II), Zn(II)or Cd(II); X = Cl-, CH3COO- or NO3- have been synthesized by template condensation of glyoxal and thiocarbohydrazide in the presence of divalent metal salts in methanolic medium. The complexes have been characterized by elemental analyses, conductance measurements, molecular weight determination, magnetic measurements, electronic, NMR, infrared and far infrared spectral studies. Electronic spectra along with magnetic moments suggest a six coordinate octahedral geometry for these complexes.

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Schiff bases have been synthesized by the reaction of p-nitrobenzaldehyde, o-nitrobenzaldehyde and p-toluyaldehyde with 4-amino-5-mercapto-1,2,4-triazole. The ligands react with Co(II), Ni(II) and Zn(II) metals to yield (1:1) and (1:2) [metal:ligand] complexes. Elemental analyses, IR, 1H NMR, electronic spectral data, magnetic susceptibility measurements, molar conductivity measurements and thermal studies have investigated the structure of the ligands and their metal complexes.

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A few (1:1) and (1:2) metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) have been isolated with ligand derived from the condensation of 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine with 2-acetylpyridine (L(1)) and characterized by elemental analysis, conductivity measurements, infrared, electronic, (1)H NMR spectral data, magnetic and thermogravimetric analyses. Due to insolubility in water and most of the common organic solvents and infusibility at higher temperatures, all the complexes are thought to be polymeric in nature. A square-planar geometry was suggested for copper(II) and octahedral proposed for cobalt(II), nickel(II) and zinc(II).

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Antibacterial Schiff bases derived from 1,2,4-triazoles as well as their metal complexes incorporating cobalt(II), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. Physico-chemical studies suggest that an octahedral geometry for the cobalt(II), nickel(II) and zinc(II)and square-planer geometry for the copper(II) complexes. These complexes have been screened for antibacterial activity against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) bacterial strains, and results compared with the activity of the free ligands.

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The regioselective synthesis of 1-heteroaryl-5-amino-4-phenylpyrazoles 3a-g and 1-heteroaryl-5-amino-3-methyl-4-phenylpyrazoles 3h-n was achieved by the treatment of heteroarylhydrazines 1a-g with alpha-phenylformylacetonitrile 2a and alpha-phenylacetylacetonitrile 2b, respectively. The structures of the compounds 3 were established by the combined use of 1H and 13C NMR spectroscopy. All the fourteen compounds were tested for their in vitro antibacterial activity against three Gram-positive and two Gram-negative bacteria.

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A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized with newly prepared biologically active ligands. These ligands were prepared by the condensation of 4-amino-5-mercapto-3-methyl-s-triazole (AMMT), 4-Amino-3-ethyl-5-mercapto-s-triazole (AEMT) with 2-acetylpyridine. The structure of the complexes have been proposed by elemental analyses, spectroscopic data i.

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Treatment of 1,1,1-trifluoromethyl-3-cyano-3-phenylpropanone (1) with several heteroarylhydrazines (2a-e) in refluxing ethanol affords 1-heteroaryl-5-amino-4-phenyl-3-trifluoromethylpyrazoles (4) in a regioselective manner. The location of trifluoromethyl group at position-3 was established by a combined use of 13C and 19F NMR spectroscopy. The reaction proceeds through the intermediacy of the hydrazone which was isolated and characterized in one case (3e) by performing the reaction at room temperature.

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Synthesis of some new 3-aryl/hetryl-5,7-dimethyl-1,2,4-triazolo[4,3-a]pyrimidines (3a-k) has been accomplished by the oxidation of 4,6-dimethyl-2-pyrimidinylhydrazones of various aldehydes with iodobenzene diacetate in dichloromethane. Nine new compounds (3b-g and 3i-k) were tested in vitro for their antibacterial activity. Two compounds, namely 3-(4'-pyridyl)-5,7-dimethyl-1,2,4-triazolo[4,3-a]pyrimidine (3k) and 3-(3',4'-dimethoxyphenyl)-5,7-dimethyl-1,2,4-triazolo[4,3-a]pyrimidine (3f), were associated with substantially higher antibacterial activity than some commercial antibiotics against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Salmonella typhi at MIC (minimum inhibitory concentration) i.

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