Plasmid Borne Resistance in Klebsiella Isolates from Kenyatta National Hospital, Nairobi, Kenya

Eighty six Klebsiella isolates from Kenyatta National Hospital and the Centre for Microbiology, Kenya Medical Research Institute, Nairobi were screened forresistance to commonly prescribed antimicrobial agents and for their plasmidcontent. Plasmids were transferred into Esherichia coli K-12 and resultingtransconjugants screened for resistance to the antimicrobial agents used onKlebsiella donors and for their plasmid content. Plasmids from the Klebsiellaisolates were also transformed into Eschericia coli and transformants analyzedfor resistance and plasmid content. Endonuclease restriction mapping was done to characterize the plasmids from Klebsiella isolates and their Eschericia coli transformants. Resistance was found to be plasmid borne and transmissible

Acquisition of naturally occurring antibody responses to recombinant protein domains of Plasmodium falciparum erythrocyte membrane protein 1

Background: Antibodies targeting variant antigens expressed on the surface of Plasmodium falciparum infected erythrocytes have been associated with protection from clinical malaria. The precise target for these antibodies is unknown. The best characterized and most likely target is the erythrocyte surface-expressed variant protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Methods: Using recombinant proteins corresponding to five domains of the expressed A4 var gene, A4 PfEMP1, the naturally occurring antibody response was assessed, by ELISA, to each domain in serum samples obtained from individuals resident in two communities of differing malaria transmission intensity on the Kenyan coast. Using flow cytometry, the correlation in individual responses to each domain with responses to intact A4-infected erythrocytes expressing A4 PfEMP1 on their surface as well as responses to two alternative parasite clones and one clinical isolate was assessed. Results: Marked variability in the prevalence of responses between each domain and between each transmission area was observed, as wasa strong correlation between age and reactivity with some but not all domains. Individual responses to each domain varied strikingly, with some individuals showing reactivity to all domains and others with no reactivity to any, this was apparent at all age groups. Evidence for possible cross-reactivity in responses to the domain DBL4γ was found. Conclusion: Individuals acquire antibodies to surface expressed domains of a highly variant protein. The finding of potential cross-reactivity in responses to one of these domains is an important initial finding in the consideration of potential vaccine targets

High-Utilisation Nanoplatinum Catalyst (Pt@cPIM) Obtained via Vacuum Carbonisation in a Molecularly Rigid Polymer of Intrinsic Microporosity

Polymers of intrinsic microporosity (PIM or here PIM-EA-TB) offer a highly rigid host environment into which hexachloroplatinate(IV) anions are readily adsorbed and vacuum carbonised (at 500 °C) to form active embedded platinum nanoparticles. This process is characterised by electron and optical microscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical methods, which reveal that the PIM microporosity facilitates the assembly of nanoparticles of typically 1.0 to 2.5-nm diameter. It is demonstrated that the resulting carbonised “Pt@cPIM” from drop-cast films of ca. 550-nm average thickness, when prepared on tin-doped indium oxide (ITO), contain not only fully encapsulated but also fully active platinum nanoparticles in an electrically conducting hetero-carbon host. Alternatively, for thinner films (50–250 nm) prepared by spin coating, the particles become more exposed due to additional loss of the carbon host. In contrast to catalyst materials prepared by vacuum-thermolysed hexachloroplatinate(IV) precursor, the platinum nanoparticles within Pt@cPIM retain high surface area, electrochemical activity and high catalyst efficiency due to the molecular rigidity of the host. Data are presented for oxygen reduction, methanol oxidation and glucose oxidation, and in all cases, the high catalyst surface area is linked to excellent catalyst utilisation. Robust transparent platinum-coated electrodes are obtained with reactivity equivalent to bare platinum but with only 1 μg Pt cm−2 (i.e. ~100% active Pt nanoparticle surface is maintained in the carbonised microporous host). [Figure not available: see fulltext.

Opsonising antibodies to P. falciparum Merozoites associated with immunity to clinical malaria

Naturally acquired humoral immunity to the malarial parasite Plasmodium falciparum can protect against disease, although the precise mechanisms remain unclear. Although antibody levels can be measured by ELISA, few studies have investigated functional antibody assays in relation to clinical outcomes. In this study we applied a recently developed functional assay of antibody-mediated opsonisation of merozoites, to plasma samples from a longitudinal cohort study conducted in a malaria endemic region of Papua New Guinea (PNG). Phagocytic activity was quantified by flow cytometry using a standardized and high-throughput protocol, and was subsequently evaluated for association with protection from clinical malaria and high-density parasitemia. Opsonising antibody responses were found to: i) increase with age, ii) be enhanced by concurrent infection, and iii) correlate with protection from clinical episodes and high-density parasitemia. Stronger protective associations were observed in individuals with no detectable parasitemia at baseline. This study presents the first evidence for merozoite phagocytosis as a correlate of acquired immunity and clinical protection against P. falciparum malaria

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research

Trypanotolerance effect as a result of genomic imprinting in F2 murine population

African tsetse-fly transmitted trypanosomosis affects a wide range of wild and domesticated animal species. Trypanotolerance, the ability of some breeds to withstand the infection has been recognized and provides a sustainable option in animal production. While a genetic contribution, several behavioural traits are not in doubt, an attempt to find the responsible genes has proven to be complicated. One advance towards generating trypanotolerant animals has been the demonstration of an effective genetic imprinting phenomenon in crossbred mice, similar to that observed following challenge. We report a novel reciprocal crossing strategy that exploits epistasis and heterosis in inbred mouse strains to identify imprinting effect controlling trypanosomosis using an F2 (129/J x C57BL/6) resource populations. The results indicate that genetic control for trypanotolerance is complicated and the identification of imprinting effect may provide new insights of introgressing trypanotolerance in livestock Kenya Veterinarian Vol. 31 (2) 2007: pp. 68-7

Fine mapping of trypanosomosis resistance loci in murine by haplotype approach

Trypanotolerance QTL has been mapped in two F2 mouse populations developed by crossing susceptible strains, A/J and BALB/c, with the resistant C57BL/6J. Identifying regions of shared haplotype in inbred lines known to harbour quantitative trait loci for disease resistance may assist to fine map the QTL locus. The 129/J mouse strain is susceptible to trypanosomosis but it is not known if it carries susceptible alleles at the previously mapped QTL. We undertook to map QTL in 138 F2 mice from 129/J x C57BL/6J crossings by selective genotyping following challenge with T. congolense. Chromosome 1 and 17 were confirmed to carry the susceptible QTL alleles previously identified in A/J and C57BL/6J strains. Chromosomes 2, 3, 5 and 15 did not show a significant QTL. Further analysis using the International SNP database suggested the presence of a shared haplotype which if confirmed, should reduce the confidence interval of the QTL on chromosome 1and 17. Kenya Veterinarian Vol. 31 (2) 2007: pp. 64-6