2001
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PublicationArticle Genetics of thermotolerance in ciprofioxacin resistant mutant of Rhizobium leguminosarum bv phaseoli(2001) Singh, R.K.A ciprofloxacin resistant mutant (CfR) of Rhizobium leguminossarum bv phaseoli USDA 2695 which nodulates common bean plants (Phaseolus vulgaris L) was isolated after nitrous acid mutagenesis. Another mutant resistant to nalidixic acid (NalR) was isolated spontaneously. Both mutants showed thermotolerance as evident by their ability to grow at elevated (40°C) temperature, although the wild type (USDA 2695) failed to grow at this temperature. Transformation and plasmid curing experiments suggested the gene(s) controlling thermotolerance (TrR) and resistance to nalidixic acid or ciprofloxacin were located on the main chromosome and not on the plasmids. High frequency of co-transfer of TrR-CrR and TrR-NalR during transformation experiments indicated a close association of these gene(s). Role of DNA gyrase and supercoiling in these thermotolerant mutants has been discussed.PublicationArticle Synthesis, characterization and biological properties of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), chromium(III) and iron(III) complexes with a new thiosemicarbazide derivative(2001) Singh, N.K.; Singh, S.B.A few complexes of N1-nicotinoyl-N4-benzoyl-3-thiosemicarbazide with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cr(III) and Fe(III) have been synthesized and characterized by elemental analyses, molar conductance, magnetic susceptibility and UV-VIS, IR, ESR, NMR (1H and 13C), FAB mass, solid state electrical conductivity and Mössbauer data. The ligand and the metal complexes have been screened against several bacteria, fungi and also for their in-vitro antitumor activity.PublicationArticle Triterpene glycoside from terminalia arjuna(Harwood Academic Publishers GmbH, 2001) Upadhyay, R.K.; Pandey, M.B.; Jha, R.N.; Singh, V.P.; Pandey, V.B.A new triterpene glycoside, arjunetoside, together with oleanolic and arjunic acids has been isolated from the root bark of Terminalia arjuna. The structure of arjunetoside has been established as 3-O-β-D-glucopyranosyl-2α,3β, 19α-trihydroxyolean-12-en-28-oic acid, 28-O-βD-glucopyranoside by chemical and spectral data.PublicationArticle Electrocatalytic characterization of new La1-xSrxCoO3 films on Pt for use as oxygen anode in alkaline solutions(2001) Singh, R.N.; Lal, B.Pure and Sr-substituted lanthanum cobaltate films have been prepared on Pt by a sol-gel derived route and their physicochemical and electrochemical properties investigated using XRD, IR, cyclic voltammetriy (CV), Tafel-polarization and impedance techniques. The films have been obtained by coating a thick colloidal solution formed by peptization of freshly prepared metal carbonate precipitate in glacial acetic acid and subsequent drying and sintering at 650°C for 2 h. The substitution of La by Sr in the perovskite lattice does not indicate any significant influence on the rate of O2 evolution reaction (OER) in 1M KOH. Values of the Tafel slope and the order for the reaction have been observed to be ∼ 2.303RT/F and ∼ 1, respectively, regardless of the nature of the oxide catalyst. The apparent electrochemical activation energy (ΔHel*) decreases linearly with increasing potential across the oxide/1M KOH interface. Values of the entropy of activation (ΔS*) for the OER are highly negative. Based on electrode kinetic results, the OER is considered to proceed with the formation of adsorbed OH radical as the intermediate in a fast step followed by its electrochemical interaction to yield physisorbed H2O2 in the slow step.PublicationArticle Proton conducting composites of heteropolyacid hydrates (phosphomolybdic and phosphotungstic acids) dispersed with insulating Al2O3(Wiley-VCH Verlag, 2001) Lakshmi, N.; Chandra, S.Composites of heteropolyacid hydrates with insulating Al2O3 as the dispersoid, viz. xPMA + (1 - x)Al2O3) and xPTA + (1 - x)Al2O3, have been prepared and characterised using DTA/TGA, XRD, IR and ion transport measurements. New exothermic peaks in the DTA for the composites with more Al2O37 and the changes in XRD suggest the probable formation of a new interface compound at the Al2O3 interface. The bulk electrical conductivity has been found to depend upon the composition, temperature and relative humidity. The composition versus conductivity isotherm exhibits two maxima at x = 0.8 and 0.6 for the PTA:Al2O3 system and x = 0.7 and 0.5 for the PMA : A12O3 system. Phenomenologically, this could be either due to the two different thresholds for the two types of mobile species (H+/H3O+ and OH-) or due to the formation of a high conducting interface compound. © WILEY-VCH Verlag Berlin GmbH.PublicationArticle Inhibition of urease from seeds of water-melon (Citrullus vulgaris) by heavy metal ions(Society for Plant Biochemistry and Biotechnology, 2001) Prakash, O.; Vishwakarma, D.K.Urease from the seeds of water melon was found to be inhibited by heavy metal ions like copper, lead, nickel and cobalt. The order of effectiveness of these metals as inhibitors was Cu2+ > Pb2+ > Ni2+ > Co2+. The inhibition by these ions was non-competitive. Time - dependent interaction of urease with nickel and cobalt exhibited a biphasic inhibition behaviour in which approximately half of the initial activity was lost rapidly (within 2 min) and remainder in a slow phase. The inhibition was largely irreversible, hence could not be reversed by dialysis. These observations are suggestive of half-and-half distribution of - SH groups on the native enzyme resulting urease into asymmetric oligomeric molecule.PublicationArticle Vitamin A as an enzyme that catalyzes the reduction of MTT to formazan by vitamin C(Wiley-Liss Inc., 2001) Chakrabarti, Ranjana; Kundu, Suman; Kumar, Sanjeev; Chakrabarti, RabindranathThe tetrazolium salt 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) is reduced to formazan by the succinate dehydrogenase system of active mitochondria, and hence, specifically used to assay for the viable cells, such as measurement of cell proliferation, cytotoxicity, and cell number. However, in the present study we have shown that some component specifically present in M199 but not in RPM1 1640 media can reduce MTT to formazan in the absence of a living system. Further study revealed that ascorbic acid reduced MTT to formazan, which was profoundly increased by a very small amount of retinol, whereas retinol alone had no effect. Oxidation of ascorbic acid by H2O2 destroyed its ability to reduce MTT. The rate of MTT reduction was directly proportional to the concentration of MTT in the absence of retinol, but approached a zero-order state beyond a certain concentration of MTT in the presence of retinol. Furthermore, retinol remained unchanged after the completion of the reaction. Taken together, these results showed that retinol acts as a reductase that catalyzes the reduction of MTT to formazan using ascorbic acid as the cosubstrate (electron donor). (C) 2000 Wiley-Liss, Inc.PublicationArticle Study of deafness in diabetics with special reference to neuropathy(2001) Jha, A.K.; Agarwal, M.K.; Singh, S.K.A total of 50 patients with diabetes mellitus were studied. Out of these, 13 patients had diabetic neuropathy on clinical evaluation. Amongst the group of patients without diabetic neuropathy, 64.86% had sensorineural hearing loss and 21.6% patients had conductive deafness. Patients with diabetic neuropathy had sensorineural hearing loss in 69.2% cases and conductive deafness in 23% patients. The hearing threshold were found to be within normal limit in diabetics with or without neuropathy at lower frequencies but it was significantly increased at higher frequencies (4000 HZ and 8000 HZ) in patients with diabetic neuropathy when compared with diabetic patients without neuropathy. The hearing threshold was increased at higher frequencies in uncontrolled diabetics. This was significant when compared with diabetics with normal fasting plasma glucose.PublicationArticle Laser Raman and IR spectra and force fields for 2,4-dichlorobenzonitrile(2001) Rastogi, V.K.; Jain, Vaibhav; Alcolea Palafox, M.; Singh, D.N.; Yadav, R.A.Raman spectrum of 2,4-dichlorobenzonitrile (2,4-DCBN) in powder form has been recorded in the region 50-4000 cm-1 on a Jasco K-500 Raman spectrophotometer using the 488.0 nm radiation from an argon laser. FTIR spectra in the region 200-4000 cm-1 have been recorded in KBr pellet and nujol mull on a Nicolet DX spectrometer. Using the observed Raman and IR frequencies, normal co-ordinate analysis has been carried out to support the vibrational analysis and to determine the planar and non-planar force fields. © 2001 Elsevier Science B.V.PublicationArticle Nomenclature of magnetic, incommensurate, composition-changed morphotropic, polytype, transient-structural and quasicrystalline phases undergoing phase transitions. II. Report of an IUCr Working Group on Phase Transition Nomenclature(International Union of Crystallography, 2001) Tolédano, J.-C.; Berry, R.S.; Brown, P.J.; Glazer, A.M.; Metselaar, R.; Pandey, D.; Perez-Mato, J.M.; Roth, R.S.; Abrahams, S.C.A general nomenclature applicable to the phases that form in any sequence of transitions in the solid state has been recommended by an IUCr Working Group [Acta Cryst. (1998). A54, 1028-1033]. The six-field notation of the first Report, hereafter I, was applied to the case of structural phase transitions, i.e. to transformations resulting from temperature and/or pressure changes between two crystalline (strictly periodic) phases involving modifications to the atomic arrangement. Extensive examples that illustrate the recommendations were provided. This second Report considers, within the framework of a similar six-field notation, the more complex nomenclature of transitions involving magnetic phases, incommensurate phases and transitions that occur as a function of composition change. Extension of the nomenclature to the case of phases with less clearly established relevance to standard schemes of transition in equilibrium systems, namely polytype phases, radiation-induced and other transient phases, quasicrystalline phases and their transitions is recommended more tentatively. A uniform notation for the translational periodicity, propagation vector or wavevector for magnetic and/or incommensurate substances is specified. The notation adopted for incommensurate phases, relying partly on the existence of an average structure, is also consistent with that for commensurate phases in a sequence. The sixth field of the nomenclature is used to emphasize the special features of polytypes and transient phases. As in I, illustrative examples are provided for each category of phase sequence. © 2001 International Union of Crystallography Printed in Great Britain - all rights reserved.PublicationArticle Studies on some new Ru(III) complexes using aryl-azo pentane-2,4-dione and 2,6-bis(2′-benzimidazolyl) pryridine as ligands: Synthesis, spectroscopic, luminescent, electrochemical and biological activities(Freund Publishing House Ltd, 2001) Mishra, Lallan; Yadaw, Ajay K.; Phadke, Ratna S.; Choi, Chang S.; Araki, KojiSome ruthenium(III) complexes with aryl-azo 2,4-pentanedione as co-ligands (L1H - L3H2) have been synthesized and characterized spectroscopically (IR, 1H NMR, UV/Vis, ESR, conductimetric) along with elemental analysis and FAB-mass data. Their luminescent and redox properties have been studied. The antibacterial, anti-HIV and antitumour activities have also been reported.PublicationArticle Inducible periplasmic chromate reducing activity in Pseudomonas aeruginosa isolated from a leather tannery effluent(2001) Ganguli, A.; Tripathi, A.K.A chromate tolerant strain of Pseudomonas aeruginosa isolated from the effluent of a tannery showed significant enzymatic activity of chromate reduction. Cells grown in chromate-supplemented medium reduced 8 μg chromate/mg protein/h in the presence of NADH/NADPH. The chromate reducing activity was inducible as cells pregrown in chromate showed higher chromate reduction. In contrast, the periplasmic fraction of cells grown in chromate reduced 75% chromate in 4 h and the spheroplast fraction failed to do so, indicating that chromate reductase may be located in the periplasm. The presence of a 30 kDa protein in the periplasmic extracts of cells grown in the presence of chromate, but its absence of the protein in cells grown without chromate, points out a possible role of this protein in chromate reduction.PublicationArticle Microstructural evolution during spray forming of an Al-18Si alloy(2001) Srivastava, V.C.; Mandal, R.K.; Ojha, S.N.The effect of the deposition distance on the nature of microstructural features of a hypereutectic Al-18Si alloy, during spray deposition, was investigated. The spray forming process employed an annular convergent-divergent nozzle to create the spray of the melt. It was found that a smaller deposition distance leads to a large scale compositional inhomogeneity in the preform.PublicationArticle Interaction of nuclear proteins with repeat sequences in the 5′ flanking region of mouse muscle creatine kinase gene during aging(Academic Press Inc., 2001) Shanti, K.; Kanungo, M.S.The 5′ flanking region of the mouse muscle creatine kinase (MCK) gene contains two repeat sequences - a mononucleotide repeat, (A)22 (-2694 to -2673), and a tetranucleotide repeat, (GTTT)8 (-2962 to -2931). We show here that these repeats in the mouse MCK gene bind to specific nuclear protein factors. Some of the factors interacting with these sequences are tissue-specific and show age-related decrease in the binding activity. Nonspecific competitor and heterologous DNA probes failed to compete out the complexes showing that the interaction is specific to the repeat sequences. These proteins may have a role in the expression of the gene during aging. © 2001 Academic Press.PublicationArticle Altered membrane fluidity and signal transduction in the platelets from patients of thrombotic stroke(2001) Srivastava, Kalyan; Dash, DebabrataSeveral earlier studies have implicated platelet activation with the pathogenesis of thrombotic stroke. In this report we have studied the changes in membrane physical microenvironment and signal transduction in the platelets obtained from the patients with thrombotic stroke. Aggregation induced by the synthetic agonist thrombin receptor-activating peptide was significantly enhanced (p < 0.001) in the platelets obtained from the patients. Steady-state fluorescence anisotropy measurements using diphenylhexatriene reflected a significant increase in membrane microviscosity from 3.315 (± 0.103) in the control to 4.600 (± 0.119) in the stroke. Proteins of relative mobilities of 131, 100, 47 and 38 kDa were found to remain phosphorylated on tyrosine in the resting platelets obtained from thrombotic stroke patients while they were not phosphorylated in the control counter-parts. Besides, calpain, a calcium dependent thiol protease present in the platelets, was found to remain active in this disease as reflected from the proteolysis of calpain substrates. Taken together, these data indicated abnormal circulating platelets in the patients of thrombotic stroke, which could contribute to the etiopathogenesis of this disease. © 2001 Kluwer Academic Publishers.PublicationArticle Synthesis, characterization and biological activity of the complexes of manganese(III), cobalt(III), nickel(II), copper(II) and zinc(II) with salicylaldehyde thiobenzhydrazone(2001) Singh, N.K.; Singh, D.K.; Singh, J.A new ligand, salcylaldehyde thiobenzhydrazone (H2STB) forms the adduct [Cu(H2STB)2]Cl2 and the deprotonated complexes, [M(HSTB)2] (M(II)=Ni, Cu or Zn), [Mn(HSTB)3] and [Co(STB)(HSTB)], which have been characterized by elemental analyses, magnetic susceptibility measurement, IR, UV-Vis, NMR and FAB mass spectral data. Magnetic and electronic spectral studies suggest octahedral geometry for [Mn(HSTB)3] and [Co(STB)(HSTB)] and square planar geometry for [M(HSTB)2] (M(II)=Ni, Cu) and [Cu(H2STB)2]Cl2. The antifungal and antibacterial activity of the ligand and the complexes have been screened against several fungi and bacteria.PublicationArticle Source rock characteristics and maturation of Palaeogene coals, Northeast India(2001) Singh, M.P.; Singh, A.K.A large number of coal samples from the Palaeogene coal deposits of Northeast India were subjected to detailed chemical (proximate, ultimate and Rock-Eval pyrolysis) and petrographic (maceral, microlithotype and vitrinite reflectance) analyses to examine their source rock characteristics and to explore their participation in hydrocarbon generation. The results show that these coals are sub-bituminous 'C' to high volatile bituminous 'C' in rank and have requisite petrographic characteristics to act as a potential source for the generation of significant amount of normal hydrocarbons. The values of vitrinite reflectance, particularly of the coals of Meghalaya and Assam, suggest a maturation close to the 'top oil window' (birth line). This indicates the possibility of expulsion of oil and condensates in the basin. However, this contention needs to be supported by organic geochemical data, maturation modelling and time of hydrocarbon generation.PublicationArticle The effect of modifiers on the fluorescence and life-time of Gd3+ ions doped in borate glasses(2001) Kumar, Akshaya; Rai, D.K.; Rai, S.B.The effect of glass modifiers on the fluorescence and life time of the 6P7/2 energy state of the Gd3+ ion has been investigated. A shift in the energy of maximum of the fluorescence has been observed. The results are explained on the basis of the relative cation and anion field strengths due to modifiers. A variation in the life-time of the 6P7/2 energy state of the Gd3+ ion has also been noted. © 2001 Elsevier Science B.V. All rights reserved.PublicationArticle Characterization of gelatin-immobilized pigeonpea urease and preparation of a new urea biosensor(2001) Srivastava, P.K.; Kayastha, A.M.; SrinivasanUrease purified from pigeonpea seeds was immobilized on gelatin beads via cross-linking with glutaraldehyde. The maximum immobilization (75%) was observed at 30 mg/ml gelatin, 0.414 mg of enzyme/bead, 1% (v/v) glutaraldehyde and 4 °C. Beads stored in 50 mM Tris/acetate buffer (pH 7.3) at 4 °C showed a half-life of 240 days and there was practically no leaching of enzyme (less than 2%) over a period of 30 days. These beads can be reused more than 30 times (with 24 h intervals) without much loss of enzyme activity (i.e. less than 11%). The immobilized urease showed a shift in its optimum pH from 7.3 to 6.5 in Tris/acetate buffer. Optimum temperature also shifted from 47 to 65 °C compared with the soluble enzyme. Gelatin-immobilized pigeonpea urease had a higher Km (8.3 mM) than that of the soluble enzyme (3.0 mM). The time-dependent temperature inactivation pattern was also found to change from biphasic to monophasic kinetics. The immobilized beads were used for the preparation of a new urea biosensor with a response time of less than 2 min. At least 14 samples of urea can be measured with this biosensor within an hour. The beads, as well as the biosensor, were used to analyse the urea content in clinical samples from the local clinical pathology laboratories. The results obtained with the biosensor were strikingly similar to those obtained with the various commonly employed biochemical/autoanalyzer® methods used. These immobilization studies also have a potential role in haemodialysis machines that maintain the urea level in kidney patients and in the construction of a portable/wearable kidney. The easy availability of the pigeonpea urease, the ease of its immobilization on gelatin and a significantly lower cost of the urease described in the present study makes it a suitable product for future applications in therapeutics and diagnostics.PublicationArticle Nitrate/nitrite reductase activity of sulfido/selenido bridged dinuclear ruthenium(III) complexes(2001) Mishra, L.; Vilaplana, R.; Singh, V.K.; Yadaw, A.K.; González-Vilchez, F.Series of dinuclear species [Ru2(L)2(LH)2-μ-S2Cl 2], [Ru2(L)2(LH)4-μ-Se2Cl 2] (L=L1H and L3H) and [Ru2(L2)2(L2H)-μ-Se 2Cl2]·2H2O, where L1H, L2H and L3H represent for 2-mercapto-5-phenyl-1,3,4-oxadiazole, 2-mercapto-benzimidazole and 2-mercapto-benzothiazole, respectively, have been prepared and characterized by their elemental analyses and spectral (IR, UV-visible, 1H NMR and FAB mass) data. The diamagnetism of these complexes are indicative of an exchange coupled dinuclear ruthenium(III) species containing S22- and Se22- bridges. The complexes along with free heterocycles (L1H-L3H) as well as RuCl3·3H20 were tested for their nitrate and nitrite reductase activities. The electrochemical behaviour of the complexes showed irreversible oxidation peaks at +(1.04-1.40) V quite comparable to those reported for sulphido bridged complexes. © 2001 Elsevier Science B.V.
