1,721,039 research outputs found
The development of a novel infection model to test CSF1-Fc as a potential therapeutic for early onset sepsis
Get PDFSepsis is a potentially fatal dysregulation of the host immune response to infection, involving stages of hyperinflammation that mediate organ damage and dysfunction. Early onset sepsis (EOS) is defined as onset within the first 72 hours after birth. It is caused by ingestion or inhalation of infected fluids either in utero or intrapartum. The only treatments currently available are antibiotics. However, with the rise in antibiotic resistance and long-term morbidities associated with antibiotic-induced dysbiosis, an alternative therapy is required. Our laboratory proposes colony stimulating factor-1 fusion protein (CSF1-Fc) as a potential host-based therapeutic, to clear the underlying infection and limit inflammation in EOS, as it has been shown to increase the maturity of macrophages. The aim of this project was to develop a novel neonatal infection model, to be utilised in future for the testing of potential therapeutics. This involved pipette-feeding bacteria to postnatal day 0 (P0) pups. Variations of this model involved administration of a mixed bacterial culture extracted from faeces that represents the maternal microbiome, or of a pure strain of Klebsiella pneumoniae to act as a clinically relevant model. Tested bacterial doses ranged from 104 – 108 colony forming units (CFU) over a 24, 48, 72 hour or 15 day infection duration. Bacterial colonisation was evaluated by plating the blood, spleen, small intestine and perianal swabs onto agar plates and counting colony forming units. Immune cell numbers were determined through haematoxylin and eosin (H&E) staining and anti-ionized calcium-binding adaptor molecule-1 (IBA1) immunohistochemistry of liver tissue sections. Contrary to our prediction, the faecal slurry and the selected strains of K. pneumoniae were unable to establish an infection and recover bacteria in a dose-dependent manner. Instead, increased virulence of the infecting agent, higher doses and a different infection timeline could be employed to improve success. Therefore, this thesis forms the basis for future investigations and informs on methodologies that require further optimisations, in order to achieve a dose-response neonatal infection model
Transcriptional regulation of B lymphocyte commitment.
No full textThe transcription factor Pax5 is essential for commitment to the B lineage as the development of these cells is arrested at an early stage in the bone marrow of Pax5 deficient mice. Pax5 deficient pro-B cells display remarkable plasticity and are able to differentiate into other cell lineages both in vitro and in vivo. Several Pax5 target genes have been previously reported but none are able to explain the developmental block observed at the early to late pro-B cell stage. To determine the exact mechanisms by which Pax5 controls B cell development, I have undertaken a cDNA microarray screen with a custom generated B cell-specific cDNA library. By identifying genes that are differentially expressed between Pax5 deficient and wild type pro-B cells, I have identified a number of potential Pax5 target genes. The microarray screen identified lymphoid-restricted membrane protein (Lrmp or Jaw1) as a novel Pax5 activated transcript. Using RT-PCR and a Pax5-estrogen receptor inducible system, I confirmed that Jaw1 is a direct Pax5 target gene whose expression is confined, in resting cells, to the earliest stages of B and T cell development. The biological relevance of Jaw1 for cell fate specification has been tested by transducing bone marrow progenitor cells with murine retroviral vectors and reconstituting haemopoiesis in vivo. I have reported that over-expression of Jaw1 in these cells results in a decrease in the development of B and NK lymphocytes and a marked increase in the development of myeloid cells in the bone marrow of reconstituted mice. This result suggests that Jaw1 may play an important role in the early development of lymphocytes in the bone marrow. Whilst initial analysis of Jaw1 deficient mice has revealed no overt defects in lymphopoiesis, I postulate that Jaw1 is involved in IP3-induced calcium signaling downstream of the pre-BCR and BCR. This hypothesis has resulted from analysis of the function of IRAG, the only known Jaw1 homologue combined with data that Jaw1 is expressed in early B cells in the BM as well as in germinal centers in the spleen. Pax5 mutant mice usually die before weaning and the cause of death is currently unknown, suggesting that Pax5 is expressed in a previously unreported tissue. To investigate this hypothesis I produced a monoclonal antibody to Pax5 and screened for novel expression domains during embryonic development and also in neonate mice. These studies did not detect any new Pax5 expression domains, but did reveal that this antibody cross-reacts with Pax2 and/or Pax8 in the developing kidney and brain. Biochemical analysis of the serum from Pax5 deficient mice also did not reveal the likely cause of death in these animals, beyond the general signs of dehydration and starvation that are likely to be secondary to the underlying defect
Microglia regulate myelin growth and integrity in the central nervous system white matter
Get PDFDisruption of myelin structure occurs with ageing and neurodegenerative
disease, and involves myelin which is outfolding, unravelling, less compact,
and thicker. This is associated with nerve dysfunction and cognitive decline;
however, the mechanisms underpinning appropriate myelin structure, i.e.
myelin integrity, are unclear.
The central nervous system (CNS)-resident macrophages microglia are prime
candidates, as they are considered to instruct maturation of the myelinproducing
oligodendrocytes and thus, myelin formation in development and
following demyelination, based on studies of microglial depletion following
loss-of-function of the pro-survival colony stimulating factor 1 receptor
(CSF1R).
As this approach also targets other CNS macrophages which may contribute
to these processes, I sought to investigate the specific roles of microglia in
regulating myelin health. To achieve this, I utilised a recently developed
transgenic mouse model, in which deletion of the FIRE super-enhancer of the
Csf1r gene (FIREΔ/Δ) leads to an absence of microglia, while other CNS
macrophages are present.
FIREΔ/Δ mice had no impairment in oligodendrocyte maturation or myelin
formation in the white matter, yet showed a loss of its integrity, with impaired
compaction, increased thickness and outfoldings and unravelling of myelin,
culminating in demyelination. Results were recapitulated by depleting
microglia in adulthood, indicating a role for microglia in myelin maintenance
rather than development. These myelin changes were associated with
impaired cognitive flexibility. Loss of myelin integrity was also observed in a
human condition (ALSP) where CSF1R mutations result in reduced white
matter microglia and dementia.
To identify the mechanism by which microglia regulate myelin integrity, singlecell
RNA sequencing of FIREΔ/Δ mice was performed, which revealed a new
oligodendrocyte subpopulation. The genes upregulated in this oligodendrocyte
population were predicted to be regulated by transforming growth factor β 1
(TGFβ1), a factor primarily produced by microglia, which regulates expression
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of its receptors e.g., TGFβR1. Accordingly, TGFβ1 levels in FIREΔ/Δ white
matter were reduced, and oligodendroglial TGFβR1 expression was
downregulated. Additionally, the conditional knockout of Tgfbr1 in mature
oligodendrocytes was sufficient to cause a loss of myelin integrity, mirroring
the results in the FIREΔ/Δ mice. Reinstating TGFβ downstream signalling via
administration of a small molecule agonist (SRI-011381) rescued the loss of
myelin integrity in FIREΔ/Δ mice, significantly reducing inner tongue
enlargement and myelin thickness versus vehicle-treated mice such that these
were comparable to wildtype controls.
My findings reveal that microglia regulate myelin health at later stages than
previously thought, preserving the structural integrity of myelin rather than
driving initial myelin formation. These findings have important implications for
understanding the pathological mechanisms underpinning loss of myelin
integrity in ageing and neurodegenerative diseases, where dysregulated
microglia may represent key therapeutic targets to restore CNS health
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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