Hospital based surveillance and genetic characterization of rotavirus strains in children (<5 years) with acute gastroenteritis in Kolkata, India, revealed resurgence of G9 and G2 genotypes during 2011–2013

AbstractIntroductionIndia accounts for an estimated 457,000–884,000 hospitalizations and 2 million outpatient visits for diarrhea. In spite of the huge burden of rotavirus (RV) disease, RV vaccines have not been introduced in national immunization programme of India. Therefore, continuous surveillance for prevalence and monitoring of the circulating genotypes is needed to assess the disease burden prior to introduction of vaccines in this region.MethodsDuring January 2011 through December 2013, 830 and 1000 stool samples were collected from hospitalized and out-patient department (OPD) patients, respectively, in two hospitals in Kolkata, Eastern India. After primary screening, the G-P typing was done by multiplex semi-nested PCR using type specific primers followed by sequencing. Phylogenetic analysis for the VP7 gene of 25 representative strains was done.ResultsAmong hospitalized and OPD patients, 53.4% and 47.5% cases were positive for rotaviruses, respectively. Unlike previous studies where G1 was predominant, in hospitalized cases G9 rotavirus strains were most prevalent (40%), followed by G2 (39.6%) whereas G1 and G12 occurred at 16.4% and 5.6% frequency. In OPD cases, the most prevalent strain was G2 (40.3%), followed by G1, G9 and G12 at 25.5%, 22.8%, 9.3%, respectively. Phylogenetically the G1, G2 and G9 strains from Kolkata did not cluster with corresponding genotypes of Rotarix, RotaTeq and Rotavac (116E) vaccine strains.ConclusionThe study highlights the high prevalence of RV in children with gastroenteritis in Kolkata. The circulating genotypes have changed over the time with predominance of G9 and G2 strains during 2011-2013. The current G2, G9 and G1 Kolkata strains shared low amino acid homologies with current vaccine strains. Although there is substantial evidence for cross protection of vaccines against a variety of strains, still the strain variation should be monitored post vaccine introduction to determine if it has any impact on vaccine effectiveness

RuIII(edta) catalyzed hydrogenation of bicarbonate to formate

Selective hydrogenation of bicarbonate to formate catalyzed by a ruthenium(III) complex, [RuIII(edta)] (edta4− = ethylenediaminetetraacetate), at moderate H2 pressure (2–8 atm) and temperature (30–40 °C) is reported. Formation of formate, the only reduction product, was identified by 13C NMR analysis of the resultant reaction mixture. Based on the spectral data, a working mechanism (admittedly speculative) involving the formation of ruthenium(III)-bicarbonate complex, [RuIII(edta)(HCO3)]2−, is proposed for the catalytic reaction

Oxidation of thiourea by peroxomonosulfate ion catalyzed by a ruthenium(III) complex: kinetic and mechanistic studies

The complex [RuIII(edta)(H2O)]− (edta4− = ethylenediaminetetraacetate) catalyzes the oxidation of thiourea (TU) by peroxomonosulfate ion (HSO5−). The kinetics of the catalytic oxidation process was studied by using stopped-flow and rapid-scan spectrophotometry as a function of [RuIII(edta)(H2O)−], [HSO5−] and [TU] at a constant pH of 6.2 (phosphate buffer) and temperature of 25 °C. Spectral and kinetic data are suggestive of a catalytic pathway involving rapid formation of a [RuIII(edta)(TU)]− intermediate complex by reaction of [RuIII(edta)(H2O)]− with TU, followed by the oxidation of the coordinated TU in which HSO5− reacts directly with the S atom of TU coordinated to the RuIII(edta) complex. Analysis of the reaction mixture at the end of the reaction revealed the formation of formamidine disulfide (TU2) as a major product; however, thiourea dioxide (TUO2) and sulfate were also observed if the reaction mixture was kept for longer time periods. A detailed mechanism in agreement with the spectral and kinetic data is presented

Oxidation of Ru(III)-Bound Thiocyanate with Peroxomonosulfate: Kinetic and Mechanistic Studies

The reaction of [RuIII(edta)(SCN)]2− (edta4− = ethylenediaminetetraacetate; SCN− = thiocyanate ion) with the peroxomonosulfate ion (HSO5−) has been studied by using stopped-flow and rapid scan spectrophotometry as a function of [RuIII(edta)], [HSO5−], and temperature (15–30ºC) at constant pH 6.2 (phosphate buffer). Spectral analyses and kinetic data are suggestive of a pathway in which HSO5− effects the oxidation of the coordinated SCN− by its direct attack at the S-atom (of SCN−) coordinated to the RuIII(edta). The high negative value of entropy of activation (ΔS≠ = −90 ± 6 J mol−1 deg−1) is consistent with the values reported for the oxygen atom transfer process involving heterolytic cleavage of the O-O bond in HSO5−. Formation of SO42−, SO32−, and OCN− was identified as oxidation products in ESI-MS experiments. A detailed mechanism in agreement with the spectral and kinetic data is presented

[RuIII(EDTA)(H2O)]- mediated oxidation of cellular thiols by HSO5-

The [RuIII(EDTA)(H2O)]- (EDTA4-= ethylenediaminetetraacetate) complex is shown to mediate the oxidation of thiols, RSH (RSH = cysteine, glutathione, N-acetylcysteine, and penicillamine), with peroxomonosulfate ion (HSO5-). The kinetics of the catalytic oxidation process were studied using toppedflow and rapid scan spectrophotometry as a function of [RuIII(EDTA)(H2O)-], [HSO5-], and [RSH] at a constant pH (6.2). Spectral analyses and kinetic data are suggestive of a catalytic pathway in which the RSH reacts with the [RuIII(EDTA)] catalyst complex to form [RuIII(EDTA)(SR)]2- intermediate species. In a subsequent step the HSO5- ion reacts directly with the coordinated S-atom of [RuIII(EDTA)(SR)]2- yielding the disulfido species, RSSR, as a major oxidation product (as identified using HPLC and ESI-MS analyses) under the employed conditions. Based on the experimental data, a working mechanism is proposed for the [RuIII(EDTA)] catalyzed oxidation of thiols

Ru(EDTA) mediated partial reduction of O2 by H2S

An effective procedure for selective reduction of O2 to H2O2 exploring the use of hydrogen sulfide, an obnoxious industrial pollutant as reductant is reported herein. The reduction of [RuIII(EDTA)pz]− (EDTA4− = ethylenediaminetetraacetate; pz = pyrazine) by hydrogen sulfide resulting in the formation of a red [RuII(EDTA)pz]2− complex (λmax = 462 nm) has been studied spectrophotometrically and kinetically using both rapid scan and stopped-flow techniques. The time course of the reaction was followed as a function of [HS−]i, pH (5.5–8.5), and temperature. Alkali metal ions were found to have a positive influence (K+ > Na+ > Li+) on the reaction rate. Kinetic data and activation parameters are interpreted in terms of a mechanism (admittedly speculative) involving outer-sphere electron transfer between the reaction partners. Reaction of the red [RuII(EDTA)pz]2− complex with molecular oxygen regenerates the [RuIII(EDTA)pz]− species in the reacting system along with the formation of H2O2, a partially reduced product of dioxygen (O2) reduction. A detailed reaction mechanism in agreement with the spectral and kinetic data is presented

Oxidation of captopril by hydrogen peroxide and peroxomonosulfate ion catalyzed by a ruthenium(III) complex: kinetic and mechanistic studies

The complex [RuIII(edta)(H2O)]− (edta4− = ethylenediaminetetraacetate) catalyzes the oxidation of captopril (CapSH) using primary oxidants, hydrogen peroxide (H2O2) and peroxomonosulfate (HSO5−). The kinetics of the oxidation reaction were studied as a function of both oxidant (H2O2, HSO5−) and substrate (CapSH) concentrations using stopped-flow and rapid scan stopped-flow techniques. Spectral and kinetic data are suggestive of a pathway involving rapid formation of the intermediate complex [RuIII(edta)(CapS)]2− followed by direct attack of the oxidant (H2O2 or HSO5−) at the S atom of the coordinated CapS−. ESI–MS and HPLC analysis of the reaction products showed that captopril disulfide (CapSSCap) is the major oxidation product. A probable mechanism in agreement with the spectral and kinetic data is presented

[RuIII(EDTA)(H2O)]− catalyzed oxidation of biologically important thiols by H2O2

[RuIII(EDTA)(H2O)]− (EDTA4− = ethylenediaminetetraacetate) catalyzes oxidation of biological thiols, RSH (RSH  =  cysteine, glutathione, N-acetylcysteine, penicillamine) using H2O2 as precursor oxidant. The kinetics of the oxidation process were studied spectrophotometrically as a function of [RuIII(EDTA)(H2O)]−, [H2O2], [RSH], and pH (4–8). Spectral analyses and kinetic data are suggestive of a catalytic pathway in which the RSH reacts with [RuIII(EDTA)] catalyst complex to form [RuIII((EDTA)(SR)]2− intermediate species. In the subsequent reaction step the oxidant, H2O2, reacts directly with the coordinated S of the [RuIII((EDTA)(SR)]2− intermediate leading to formation of the disulfido (RSSR) oxidation product (identified by HPLC and ESI-MS studies) of thiols (RSH). Based on the experimental results, a working mechanism involving oxo-transfer from H2O2 to the coordinated thiols is proposed for the catalytic oxidation

Ru^III(edta) catalyzed hydrogenation of bicarbonate to formate

<p>Selective hydrogenation of bicarbonate to formate catalyzed by a ruthenium(III) complex, [Ru^III(edta)] (edta⁴⁻ = ethylenediaminetetraacetate), at moderate H₂ pressure (2–8 atm) and temperature (30–40 °C) is reported. Formation of formate, the only reduction product, was identified by ¹³C NMR analysis of the resultant reaction mixture. Based on the spectral data, a working mechanism (admittedly speculative) involving the formation of ruthenium(III)-bicarbonate complex, [Ru^III(edta)(HCO₃)]²⁻, is proposed for the catalytic reaction.</p