Prevalence in Britain of abnormal prion protein in human appendices before and after exposure to the cattle BSE epizootic

Widespread dietary exposure of the population of Britain to bovine spongiform encephalopathy (BSE) prions in the 1980s and 1990s led to the emergence of variant Creutzfeldt-Jakob Disease (vCJD) in humans. Two previous appendectomy sample surveys (Appendix-1 and -2) estimated the prevalence of abnormal prion protein (PrP) in the British population exposed to BSE to be 237 per million and 493 per million, respectively. The Appendix-3 survey was recommended to measure the prevalence of abnormal PrP in population groups thought to have been unexposed to BSE. Immunohistochemistry for abnormal PrP was performed on 29,516 samples from appendices removed between 1962 and 1979 from persons born between 1891 through 1965, and from those born after 1996 that had been operated on from 2000 through 2014. Seven appendices were positive for abnormal PrP, of which two were from the pre-BSE-exposure era and five from the post BSE-exposure period. None of the seven positive samples were from appendices removed before 1977, or in patients born after 2000 and none came from individuals diagnosed with vCJD. There was no statistical difference in the prevalence of abnormal PrP across birth and exposure cohorts. Two interpretations are possible. Either there is a low background prevalence of abnormal PrP in human lymphoid tissues that may not progress to vCJD. Alternatively, all positive specimens are attributable to BSE exposure, a finding that would necessitate human exposure having begun in the late 1970s and continuing through the late 1990s

Prevalent abnormal prion protein in human appendixes after bovine spongiform encephalopathy epizootic:large scale survey

To carry out a further survey of archived appendix samples to understand better the differences between existing estimates of the prevalence of subclinical infection with prions after the bovine spongiform encephalopathy epizootic and to see whether a broader birth cohort was affected, and to understand better the implications for the management of blood and blood products and for the handling of surgical instruments

Prolonged immune alteration following resolution of acute inflammation in humans.

Acute inflammation is an immediate response to infection and injury characterised by the influx of granulocytes followed by phagocytosing mononuclear phagocytes. Provided the antigen is cleared and the immune system of the host is fully functional, the acute inflammatory response will resolve. Until now it is considered that resolution then leads back to homeostasis, the physiological state tissues experienced before inflammation occurred. Using a human model of acute inflammation driven by intradermal UV killed Escherichia coli, we found that bacteria and granulocyte clearance as well as pro-inflammatory cytokine catabolism occurred by 72h. However, following a lag phase of about 4 days there was an increase in numbers of memory T cells and CD163+ macrophage at the post-resolution site up to day 17 as well as increased biosynthesis of cyclooxygenase-derived prostanoids and DHA-derived D series resolvins. Inhibiting post-resolution prostanoids using naproxen showed that numbers of tissue memory CD4 cells were under the endogenous control of PGE2, which exerts its suppressive effects on T cell proliferation via the EP4 receptor. In addition, we re-challenged the post-resolution site with a second injection of E. coli, which when compared to saline controls resulted in primarily a macrophage-driven response with comparatively fewer PMNs; the macrophage-dominated response was reversed by cyclooxygenase inhibition. Re-challenge experiments were also carried out in mice where we obtained similar results as in humans. Therefore, we report that acute inflammatory responses in both humans and rodents do not revert back to homeostasis, but trigger a hitherto unappreciated sequence of immunological events that dictate subsequent immune response to infection.Wellcome Trust Senior Research Fellowship (Grant number: WT087520), Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant number: 107613/Z/15/Z) and the Barts Charity (Grant number: MGU0343)

Nano-Crystalline &Amorphous Silicon PhotoTransistor Performance Analysis

In this thesis, we compared electrical performance and stability of a novel nanocrystalline Si (nc-Si) thin film phototransistor (TFT) phototransistor and a regular amorphous silicon (a-Si:H) TFT phototransistor for large area imaging applications. The electrical performance parameters of nc-Si TFT phototransistor were extracted from the electrical (current-voltage) testing in dark and under illumination. The field-effect mobility is found to be around 1.2 cm2V-1s-1, the threshold voltage around 3.9V and the sub-threshold voltage slope around 0.47V/Dec. Optical properties of nc-Si TFT phototransistor have been evaluated under the green light illumination in the range of 1014 – 1017 lum, and the photocurrent gain and the external quantum efficiency were extracted from the experimental results. By comparing the results with those for a-Si:H TFTs measured under the same conditions, we found that nc-Si TFT has higher photo current gain under low illumination intensity, 5 ×1014 to 7 ×1015 lum. This thesis shows the relations bewteen the photo current gain, the external quantum efficiency, TFT drain and TFT gate bias; the photo current gain and the external quantum efficiency can be controlled by the Vds and the Vgs

Generation of brain tumours in mice by Cre-mediated recombination of neural progenitors in situ with the tamoxifen metabolite endoxifen

Targeted cell- or region-specific gene recombination is widely used in the functional analysis of genes implicated in development and disease. In the brain, targeted gene recombination has become a mainstream approach to study neurodegeneration or tumorigenesis. The use of the Cre-loxP system to study tumorigenesis in the adult central nervous system (CNS) can be limited, when the promoter (such as GFAP) is also transiently expressed during development, which can result in the recombination of progenies of different lineages. Engineering of transgenic mice expressing Cre recombinase fused to a mutant of the human oestrogen receptor (ER) allows the circumvention of transient developmental Cre expression by inducing recombination in the adult organism. The recombination of loxP sequences occurs only in the presence of tamoxifen. Systemic administration of tamoxifen can, however, exhibit toxicity and might also recombine unwanted cell populations if the promoter driving Cre expression is active at the time of tamoxifen administration. Here, we report that a single site-specific injection of an active derivative of tamoxifen successfully activates Cre recombinase and selectively recombines tumour suppressor genes in neural progenitor cells of the subventricular zone in mice, and we demonstrate its application in a model for the generation of intrinsic brain tumours

Post-resolution tissue accumulation of macrophages.

<p>Acute inflammation was triggered in the ventral aspect of forearm of healthy volunteers by the intradermal injection of 1.5 x 10⁷ UV-killed <i>E</i>. <i>coli</i> (UVKEc) suspended in 100 μl of sterile saline. A suction blister was raised over the inflamed site at the specified interval to collect the inflammatory exudate. Exudate was centrifuged to separate cells from the supernatant. The immune cell subsets were identified by polychromatic flow cytometry. The numbers of CD14⁺ mononuclear cells at the specified interval are shown here <b>(A)</b>. A 3mm skin punch biopsy was taken from the inflamed site under local anaesthesia at the specified interval and the formalin fixed paraffin embedded (FFPE) skin sections were probed by immunohistochemistry for CD163. The representative sections are shown here <b>(B).</b> MCP-1, IP-10, MDC and MCP-4 <b>(panels C-F)</b> in the cell free exudate were measured using multiplex ELISA and their concentrations in the exudate at the specified intervals are shown here <b>(C)</b>. n = 3 for each time point. Data presented as mean ± SEM.</p

Comparative expression analysis reveals lineage relationships between human and murine gliomas and a dominance of glial signatures during tumor propagation in vitro

Brain tumors are thought to originate from stem/progenitor cell populations that acquire specific genetic mutations. Although current preclinical models have relevance to human pathogenesis, most do not recapitulate the histogenesis of the human disease. Recently, a large series of human gliomas and medulloblastomas were analyzed for genetic signatures of prognosis and therapeutic response. Using a mouse model system that generates three distinct types of intrinsic brain tumors, we correlated RNA and protein expression levels with human brain tumors. A combination of genetic mutations and cellular environment during tumor propagation defined the incidence and phenotype of intrinsic murine tumors. Importantly, in vitro passage of cancer stem cells uniformly promoted a glial expression profile in culture and in brain tumors. Gene expression profiling revealed that experimental gliomas corresponded to distinct subclasses of human glioblastoma, whereas experimental supratentorial primitive neuroectodermal tumors (sPNET) correspond to atypical teratoid/rhabdoid tumor (AT/RT), a rare childhood tumor.</p

Acute inflammatory response to intradermal UVkEc injection.

<p>Acute inflammation was triggered in the ventral aspect of forearm of healthy volunteers by the intradermal injection of 1.5 x 10⁷ UV-killed <i>E</i>. <i>coli</i> (UVKEc) suspended in 100 μl of sterile saline. Vascular hyperaemia at the site was assessed by laser Doppler imager and the representative flux images after a specified time point are shown here <b>(A)</b>. A 3 mm skin punch biopsy was taken from the inflamed site under local anaesthesia at the specified interval and formalin fixed paraffin embedded (FFPE) skin sections were probed by immunohistochemistry for <i>E</i>. <i>coli</i> LPS. The representative sections are shown here <b>(B)</b>. A suction blister was raised over the inflamed site at the specified interval to collect the inflammatory exudate. Exudate was centrifuged to separate cells from the supernatant. The immune cell subsets were identified by polychromatic flow cytometry. The total count/ml of neutrophils in the inflammatory exudate at specified interval is shown here <b>(C)</b>. IL-6, TNFα and IL1β in the cell free exudate were measured using multiplex ELISA and their concentrations in the exudate at the specified intervals are shown here <b>(D-F, respectively)</b>. n = 3 for each time point. Data presented as mean ± SEM.</p

Increased lipid mediator biosynthesis during post-resolution biology.

<p>Acute inflammation was triggered in the ventral aspect of forearm of healthy volunteers by the intradermal injection of 1.5 x 10⁷ UV-killed <i>E</i>. <i>coli</i> (UVKEc) suspended in 100 μl of sterile saline. A suction blister was raised over the inflamed site at the specified interval to collect the inflammatory exudate. Lipid mediators in the cell free exudate were analysed by liquid chromatography tandem mass spectrophotometry (LC MS/MS). The levels of PGE₂ <b>(A)</b>, TXB₂ <b>(B),</b> PGD₂ <b>(C),</b> PGF_2α <b>(D),</b> LXB₄ <b>(E)</b>, 5,15-diHETE <b>(F)</b>, RvD5 <b>(G)</b>, 5,15 diHETE (G) and RvE3 <b>(H)</b> at specified interval are shown here. n = 3 for each time point. Data presented as mean ± SEM.</p