Thesis (Ph. D.)--University of Queensland, 2001. / Privately bound. Includes bibliographical references.

Thesis (M.D.)--University of Hong Kong, 1984.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 221-251.

B cell development is a highly organized process, which commences in the fetal liver during embryogenesis and in the bone marrow (BM) after birth. Surface IgM+ immature B cells emigrate from the BM via the blood stream to the spleen and finally differentiate into conventional mature follicular B (FoB) cells and marginal zone (MZ) B cells. Conversely, some sIgM+ immature B cells can also mature into IgD+ FoB cells in the BM. The ubiquitously expressed cell surface glycoprotein CD47 and its receptor signal regulatory protein α (SIRPα) are members of the immunoglobulin superfamily. Both individually and upon their interaction, CD47 and SIRPα have been found to play important role in the homeostasis of T lymphocytes or CD8­ conventional dendritic cells (cDCs) in secondary lymphoid organs. However, their role in regulating B cell homeostasis has remained unknown. The present study describes important roles of CD47 and SIRPα in B cell homeostasis. Lack of SIRPα signaling in adult SIRPα mutant (MT - cytoplasmic domain deletion) mice resulted in an impaired B cell maturation in the BM and spleen, which was also reflected in the blood. In the BM and spleen of SIRPα MT mice, reduced numbers of semi-mature IgD+IgMhi follicular type-II (F-II) and mature IgD+IgMlo follicular type-I (F-I) B cells were observed, while earlier BM B cell progenitors or splenic transitional B cells remained unaltered. In SIRPα MT mice, maturing B cells in BM and spleen were found to express higher levels of the pro-apoptotic protein BIM and contained an increased level of apoptotic cells. In contrast to that for FoB cells, the splenic MZ B cell population was increased with age in SIRPα MT mice without showing an increased level of activation markers. Immunohistochemical analysis revealed an increased follicular localization of MZ B cells in the spleens of SIRPα MT mice. In addition, MZ macrophages and marginal metallophilic macrophages were not restricted to their normal position in SIRPα MT spleens. Interestingly, CD47-deficient (CD47-/-) mice mimicked the FoB cell phenotype observed in SIRPα MT mice and had a reduced number of  FoB cells in the BM, blood and the spleen at 5­6 months of age, but not in younger mice. Similar to SIRPα MT mice, CD47-/- mice also displayed an increased number of splenic MZ B cells. Sera form both mouse strains did not show any signs of an increased production of autoantibodies or antinuclear antigens. BM reconstitution experiments identified a requirement for non-hematopoietic SIRPα signaling for normal B cell maturation in the BM and to maintain normal numbers and retention of MZ B cells in the splenic MZ. On the contrary, hematopoietic SIRPα signaling appeared to be important for FoB cell maturation in the spleen. Interestingly, hematopoietic SIRPα was required for normal MZ retention of MZ macrophages while normal distribution of metallophilic macrophages required non­hematopoietic SIRPα signaling.  Collectively, these findings revealed an important role of CD47 and of SIRPα signaling in B cell homeostasis in different lymphoid organs.

This dissertation presents a measurement of the W+b-jets \((pp → W + b(\bar{b}) + X)\) production cross-section in proton–proton collisions at a center-of-mass energy of 7 TeV at the LHC. The results are based on data corresponding to an integrated luminosity of \(4.6 fb^{−1}\), collected with the ATLAS detector. The measurement probes the QCD sector of the Standard Model at high energy, in a region where b-quark mass and double parton scattering play an important role. In addition, the measurement is relevant for searches for physics beyond the Standard Model in final states with a W boson and b-jets. The measurement relies on the leptonic decay modes of the W, and on the iden- tification of b-jets. The backgrounds to the W+b-jets process are estimated using Monte Carlo simulation and data-driven techniques. Cross-sections, corrected for all known detector effects and quoted in a limited kinematic range, are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for both the muon and electron decay modes of the W boson. / Physics

published_or_final_version / Medicine / Master / Doctor of Medicine

published_or_final_version / Surgery / Master / Master of Research in Medicine

Πραγματοποιήσαμε πολυσταδιακή δειγματοληπτική έρευνα, προκειμένου να μελετήσουμε τον επιπολασμό και τις οδούς μετάδοσης της ηπατίτιδας Β και C στο γενικό πληθυσμό του Νομού Αχαΐας. Για το σκοπό αυτό εξετάσαμε αντιπροσωπευτικό δείγμα 1500 ατόμων χρησιμοποιώντας τρίτης γενιάς αντιδραστήρια. Δείκτες HBV μόλυνσης διαπιστώθηκαν σε 339 άτομα (22,6%) με επιπολασμό anti-HBc αντισωμάτων 21,6% (95%CI:19,5-23,8) και HBsAg αντιγόνου 2,1% (95%CI:1,5-3). Anti-HCV θετικά αντισώματα διαπιστώθηκαν σε 8 άτομα με ELISA-3 (0,5%, 95%CI:0,2-1,1), από τα οποία 5 (62,5%) επιβεβαιώθηκαν με LIA-3 και 3 (37,5%) είχαν PCR θετική. Συλλοίμωξη ή παρελθούσα μόλυνση και από τους δύο ιούς ανιχνεύτηκε σε 5 άτομα (0,3%). Από τη στατιστική σύγκριση που έγινε διαπιστώθηκε αυξημένη HBV μόλυνση σε στατιστικά σημαντικό βαθμό στους άνδρες, στους πλέον ηλικιωμένους, στους εγγάμους/διαζευγμένους/χήρους, σε άτομα χαμηλότερου επιπέδου μόρφωσης, με >2 παιδιά, με συγκατοίκηση <2 άτομα καθώς και στις ορεινές και αγροτικές περιοχές έναντι των αστικών και πεδινών. Επίσης, το θετικό περιβάλλον, η κατάχρηση αλκοόλ, η ύπαρξη σεξουαλικών σχέσεων και η μη χρήση προφυλακτικού τόσο με τον περιστασιακό όσο και με το μόνιμο σύντροφο ήταν παράγοντες κινδύνου της μόλυνσης από ιό Β. Αντίθετα, δε βρέθηκε στατιστικώς σημαντική διαφορά HBV μόλυνσης σε σχέση με τις μεταγγίσεις και τη νοσηλεία >1d. Από την άποψη της επαγγελματικής κατανομής της Β μόλυνσης, ιδιαίτερα επιβαρημένη ήταν η αγροτική και η εργατική τάξη. Πάντως, από την πολυπαραγοντική ανάλυση που ακολούθησε μόνο το άρρεν φύλο (ΣΚ 4,1, 95%CI:2,4-7,1), η αυξημένη ηλικία (≥30 ετών ΣΚ 9, 95%CI:4,2-19,4) και το θετικό περιβάλλον (ΣΚ 1,3, 95%CI:0,9-1,8) είχαν ανεξάρτητη σχέση με την HBV μόλυνση. Η γενετήσια και η ενδοοικογενειακή οδός αποτελούσαν τους συχνότερους τρόπους διασποράς του ιού Β, ενώ η παρεντερική οδός ήταν η κυρίαρχη στην μετάδοση του ιού C. Χρόνια ηπατίτιδα Β διαπιστώθηκε στο 9,5% των HBsAg θετικών που ελέγχτηκαν στο Τμήμα Λοιμώξεων (σε κανέναν δεν ανιχνεύτηκε HBV-DNA ιαιμία), ενώ το 60% των επιβεβαιωμένων anti-HCV θετικών έπασχε από χρόνια ηπατίτιδα C. Εμβολιασμό έναντι της ηπατίτιδας Β δήλωσαν 183 άτομα (12,2%), στο 85,8% μαθητές και H.C.W, και anti-HBs>10mIU/ml ανιχνεύτηκαν στο 83,6%. Τέσσερα άτομα (2,2% των εμβολιασθέντων) παρουσίασαν και δείκτες παρελθούσας HBV μόλυνσης. Η «αποτυχία» του εμβολίου υπολογίστηκε στο 7,5%. Οι άνδρες, παρά τον τετραπλό κίνδυνο μόλυνσης, εμβολιάζονταν σε μικρότερο βαθμό συγκριτικά με τις γυναίκες, ενώ δεν υπήρχε στατιστικώς σημαντική διαφορά εμβολιασμού μεταξύ αυτών που είχαν θετικό και αρνητικό περιβάλλον. Συμπερασματικά, ο Νομός Αχαΐας κατατάσσεται στις ενδιάμεσης ενδημικότητας περιοχές όσον αφορά στην ηπατίτιδα Β και στις χαμηλής ενδημικότητας όσον αφορά στην ηπατίτιδα C. Οι κύριοι οδοί μετάδοσης είναι η γενετήσια και η ενδοοικογενειακή για τον ιό Β και η παρεντερική για τον ιό C. Παρά την πολύ μικρή συχνότητα στο γενικό πληθυσμό και λόγω του υψηλού ποσοστού μετάπτωσης σε χρονιότητα, η ηπατίτιδα C παίζει όχι μόνο εξίσου σημαντικό αλλά ίσως και πρωταγωνιστικό ρόλο στη νοσηρότητα από χρόνια ιογενή ηπατοπάθεια στην περιοχή μας. Ειδικά για την ηπατίτιδα Β, η υιοθέτηση του μαζικού εμβολιασμού θα αλλάξει το επιδημιολογικό τοπίο, αλλά χρειάζεται παράλληλα πιο ικανοποιητική κάλυψη των ομάδων υψηλού κινδύνου. / A community-based survey was conducted using the multistage random sampling method, in order to determine the prevalence and routes of transmission of hepatitis B and C in the general population of Achaia region in the Southwestern Greece. For this purpose we examined a representative sample of 1500 individuals using third generation assays. HBV infection markers were detected in 339 subjects (22,6%) with anti-HBc prevalence 21,6% (95%CI:19,5-23,8) and HBsAg prevalence 2,1% (95%CI:1,5-3). Anti-HCV antibodies were detected in 8 subjects with ELISA-3 (0,5%, 95%CI:0,2-1,1), 5 of which (62,5%) were confirmed with LIA-3 and 3 (37,5%) were HCV-RNA positive. Dual or past infection with both viruses was detected in 5 subjects (0,3%). Male sex, older age, married/divorced/widowed family status, lower level of education, more than two children, cohabitation with less than two persons, positive environment, alcohol abuse, sex, absence of condom prophylaxis during sexual intercourse with single or multiple partners were all risk factors for HBV infection (statistically significant). On the contrary, there was not significant difference between HBV-negative and HBVinfected individuals when transfusions or hospitalization >1d were concerned. Workers and people in the agricultural sector were particularly affected. Nevertheless, multivariate statistical analysis revealed that male sex (RR 4,1, 95%CI:2,4-7,1), older age (≥30y RR 9, 95%CI:4,2-19,4) and positive environment (RR 1,3, 95%CI:0,9-1,8) were the only independently associated with HBV infection risk factors. Sexual and intrafamiliar exposure were the commonest ways for HBV transmission, while percutaneous exposure was the main route for HCV transmission. Chronic hepatitis B was diagnosed in 9,5% of HBsAg carriers who were examined by the physicians of the Department of Infectious Diseases (nobody was HBV-DNA positive), while 60% of those with confirmed anti-HCV antibodies had chronic hepatitis C. 183 subjects declared B immunization (12,2%), mostly pupils and health care workers (85,8%), and anti-HBs>10mIU/ml were detected in 83,6% of them. Four (2,2%) had, also, positive markers of past HBV infection. Vaccination failure was estimated at 7,5%. Men, despite their fourfold risk of infection, were immunized at a lower rate than women, while there was not significant difference in immunization rate between those with positive and negative environment. In conclusion, Achaia region can be classified as an intermediate HBV and a low HCV endemicity area. The main routes of HBV and HCV transmission are the sexual/intrafamiliar and percutaneous respectively. Despite the very low prevalence of hepatitis C and due to its higher range of chronicity, the number of chronically HBV and HCV infected in the general population seem to be comparable and, even, hepatitis C can play a leading role in chronic viral liver disease in our region. As far as hepatitis B is concerned, the adoption of mass immunization programmes will alter the epidemiological landscape and this should be especially encouraged in persons belonging to high risk groups.

Two trials were carried out to evaluate the effect of inclusion level of canola meal derived from Brassica (B.) napus and B. juncea on cattle performance and nutrient utilization. Trial 1 consisted of backgrounding (54 d) and finishing (153 d) phases. The control diet for the backgounding (BK) phase consisted of 39% barley silage, 30.4% barley grain, 22.8% brome grass hay and 7.8% supplement (DM). Treatments consisted of B. napus or B. juncea at 15 or 30% (DM) inclusion, replacing barley grain. The finishing control diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% supplement (DM). Treatments consisted of B. napus or B. juncea at 10 or 20% (DM) inclusion, replacing barley grain. During BK, dry matter intake (DMI), average daily gain (ADG), gain: feed (G:F) increased linearly (P < 0.01) as the level of inclusion of B. juncea meal increased. Cattle fed B. napus meal showed a quadratic response (P = 0.05) in DMI and linear increase (P = 0.02) in ADG with increasing inclusion. During finishing, DMI increased linearly (P = 0.05) for cattle fed B. juncea meal while a quadratic response (P = 0.02) was seen with B. napus meal. Feed efficiency and NEg content of the diet (P ≤ 0.02) decreased linearly with increasing inclusion of both meals. Trial 2 evaluated dietary rumen fermentation and total tract digestibility characteristics in a 5 x 5 Latin Square Design. Diets were similar to finishing phase of Trial 1. There was no effect of treatment on rumen pH, however a linear increase in acetate (P ≤ 0.01), ammonia (P < 0.01) and decrease (P < 0.01) in propionate was seen with both meal types. Crude protein and acid detergent fiber digestibility increased (P = 0.03) linearly with increasing inclusion of B. juncea meal. The results indicate that canola meal derived from B. napus and B. juncea is not suitable as a supplemental energy source replacing for barley grain in finishing diets but canola meal from B. juncea can be fed at levels up to 30% of the DM in backgrounding diets if priced appropriately.

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