132 research outputs found

    Population genetic structure of Streptococcus pneumoniae in Kilifi, Kenya, prior to the introduction of pneumococcal conjugate vaccine.

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    BACKGROUND: The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in Kenya in 2011. Introduction of any PCV will perturb the existing pneumococcal population structure, thus the aim was to genotype pneumococci collected in Kilifi before PCV10. METHODS AND FINDINGS: Using multilocus sequence typing (MLST), we genotyped >1100 invasive and carriage pneumococci from children, the largest collection genotyped from a single resource-poor country and reported to date. Serotype 1 was the most common serotype causing invasive disease and was rarely detected in carriage; all serotype 1 isolates were members of clonal complex (CC) 217. There were temporal fluctuations in the major circulating sequence types (STs); and although 1-3 major serotype 1, 14 or 23F STs co-circulated annually, the two major serotype 5 STs mainly circulated independently. Major STs/CCs also included isolates of serotypes 3, 12F, 18C and 19A and each shared ≤ 2 MLST alleles with STs that circulate widely elsewhere. Major CCs associated with non-PCV10 serotypes were predominantly represented by carriage isolates, although serotype 19A and 12F CCs were largely invasive and a serotype 10A CC was equally represented by invasive and carriage isolates. CONCLUSIONS: Understanding the pre-PCV10 population genetic structure in Kilifi will allow for the detection of changes in prevalence of the circulating genotypes and evidence for capsular switching post-vaccine implementation

    Statistical quality assessment and outlier detection for liquid chromatography-mass spectrometry experiments

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    <p>Abstract</p> <p>Background</p> <p>Quality assessment methods, that are common place in engineering and industrial production, are not widely spread in large-scale proteomics experiments. But modern technologies such as Multi-Dimensional Liquid Chromatography coupled to Mass Spectrometry (LC-MS) produce large quantities of proteomic data. These data are prone to measurement errors and reproducibility problems such that an automatic quality assessment and control become increasingly important.</p> <p>Results</p> <p>We propose a methodology to assess the quality and reproducibility of data generated in quantitative LC-MS experiments. We introduce quality descriptors that capture different aspects of the quality and reproducibility of LC-MS data sets. Our method is based on the Mahalanobis distance and a robust Principal Component Analysis.</p> <p>Conclusion</p> <p>We evaluate our approach on several data sets of different complexities and show that we are able to precisely detect LC-MS runs of poor signal quality in large-scale studies.</p

    Comparative Economic Evaluation of Haemophilus influenzae Type b Vaccination in Belarus and Uzbekistan

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    BACKGROUND: Hib vaccine has gradually been introduced into more and more countries during the past two decades, partly due to GAVI Alliance support to low-income countries. However, since Hib disease burden is difficult to establish in settings with limited diagnostic capacities and since the vaccine continues to be relatively expensive, some Governments remain doubtful about its value leading to concerns about financial sustainability. Similarly, several middle-income countries have not introduced the vaccine. The aim of this study is to estimate and compare the cost-effectiveness of Hib vaccination in a country relying on self-financing (Belarus) and a country eligible for GAVI Alliance support (Uzbekistan). METHODS AND FINDINGS: A decision analytic model was used to estimate morbidity and mortality from Hib meningitis, Hib pneumonia and other types of Hib disease with and without the vaccine. Treatment costs were attached to each disease event. Data on disease incidence, case fatality ratios and costs were primarily determined from national sources. For the Belarus 2009 birth cohort, Hib vaccine is estimated to prevent 467 invasive disease cases, 4 cases of meningitis sequelae, and 3 deaths, while in Uzbekistan 3,069 invasive cases, 34 sequelae cases and 341 deaths are prevented. Estimated costs per discounted DALY averted are US9,323inBelarusandUS 9,323 in Belarus and US 267 in Uzbekistan. CONCLUSION: The primary reason why the cost-effectiveness values are more favourable in Uzbekistan than in Belarus is that relatively more deaths are averted in Uzbekistan due to higher baseline mortality burden. Two other explanations are that the vaccine price is lower in Uzbekistan and that Uzbekistan uses a three dose schedule compared to four doses in Belarus. However, when seen in the context of the relative ability to pay for public health, the vaccine can be considered cost-effective in both countries

    Capacity for microtubule reorganization and cell wall synthesis in cytoplasts of the green alga Mougeotia

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    A small proportion of nucleate subprotoplasts (karyoplasts) and enucleate subprotoplasts (cytoplasts) are formed during the preparation of protoplasts from the filamentous green alga Mougeotia . Regeneration of Mougeotia protoplasts is an orderly process known to involve reorganisation of cortical microtubules into polar arrays centered upon two opposing foci, synthesis of new cell walls and elongation to reform cylindrical cells. The ability of cytoplasts to carry out microtubule reorganisation and cell wall synthesis was investigated by combining Hoechst staining, to distinguish cytoplasts from karyoplasts and protoplasts, with immunofluorescent staining of microtubules and Calcofluor or Tinopal staining of cell walls. Cytoplasts survived at least 20 h in culture, but did not elongate. However, cytoplasts did participate in the first steps of protoplast regeneration. The majority of cytoplasts synthesized some cell wall material, while a small proportion was able to form ordered arrays of cortical microtubules indistinguishable from those in regenerating nucleate protoplasts. These results demonstrate the ability of plant microtubules to form new, orderly arrays in the absence of a nucleus, and suggest that the reestablishment of axiality in the protoplasts does not require a nucleus or nuclear DNA transcription.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41730/1/709_2005_Article_BF01404116.pd
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