Thesis--Copenhagen. / Includes bibliographical references.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Feb. 26, 2009). Includes bibliographical references.

No description available.

ABO- och Rh-systemet är de mest kliniskt betydelsefulla blodgruppssystem för nutidens serologiska diagnostik. En viktig analysmetod inom detta område är kvantifiering av blodgruppsantikroppar då mängden antikroppar i plasma bestäms. Denna metod har flera olika användningsområden, bland annat för att bestämma mängden av irreguljära antikroppar för gravida vid immunisering då mamman har bildat antikroppar mot ett antigen som fostret har. Metoden utförs även i samband med transplantationer och för trombocytgivare. Kvantifiering av blodgruppsantikroppar kan utföras både manuellt och automatiskt. Den manuella metoden utförs med diluent pH7, en form av fosfatbuffrad saltlösning (PBS), som spädningsvätska, medan den automatiska utförs med en dyrare titreringslösning. Ett mer kostnadseffektivt val skulle vara att använda diluent pH7 som spädningsvätska för den automatiska metoden. Denna studie är en metodoptimering för automatisk titrering av blodgruppsantikroppar med IH-500 instrument. Plasmaprover från tre olika kategorier av individer (transplantationspatienter, trombocytgivare och gravida kvinnor) analyserades på IH-500 instrument för både ABO- och andra blodgruppsantikroppar. I maskinen utförs en spädningsserie av plasma från patienter och efter tillsättning av testerytrocyter observeras var det skett en agglutination och hur starkt den var. Det första spädningssteget som graderas som 1+ reaktion räknas som antikroppstitern. Resultat redovisades i form av stapeldiagram som visar skillnaden i antikroppstiter med både titreringslösning och PBS som spädningsvätska. Samtliga resultat ligger inom ramen för vad som definierats som ett godkänt resultat. Konklusionen av studien är att PBS är ett effektivt och billigare alternativ som kan användas som spädningsvätska vid automatisk titrering av ABO- och andra blodgruppsantikroppar på IH-500 instrument. / The ABO and Rh blood group systems are the most clinically significant blood group systems for contemporary serological diagnostics. A vital analysis method in this area is the quantification of blood group antibodies, where the amount of antibodies in plasma is determined. This method has several different uses, including the determination of irregular antibodies in pregnant women suspected of immunization if the mother has developed antibodies against an antigen that the fetus possesses. The method is also performed in connection with transplants and for platelet donors. Quantification of blood group antibodies can be performed both manually and automatically. The manual method utilizes diluent pH7, a form of phosphate-buffered saline (PBS), as the diluent, while the automatic method is performed with a more expensive titration solution. A more cost-effective choice would be to use diluent pH7 as the diluent for the automatic method. This study aims to optimize the method for automatic titration of blood group antibodies using the IH-500 instrument. Plasma samples from three different categories of individuals (transplant patients, platelet donors and pregnant women) were analyzed on the IH-500 instrument for both ABO and other blood group antibodies. From patient plasma samples a dilution series was made, and after adding test erythrocytes the level of agglutination was observed. The first dilution step graded as 1+ reaction is counted as the antibody titer. Results were presented in the form of bar graphs illustrating the difference in antibody titers with both titration solution and PBS as the diluent. All results fall within the range of what has been defined as an acceptable result. The conclusion of the study is that PBS is an effective and inexpensive alternative that can be used as the diluent for automatic titration of ABO and other blood group antibodies on the IH-500 instrument.

Submitted by Fabíola Silva (fabiola.silva@famerp.br) on 2018-02-07T18:29:25Z No. of bitstreams: 1 ulissescamargo_tese.pdf: 700757 bytes, checksum: 68231dab9197a8717320c0e887f2b2f6 (MD5) / Made available in DSpace on 2018-02-07T18:29:25Z (GMT). No. of bitstreams: 1 ulissescamargo_tese.pdf: 700757 bytes, checksum: 68231dab9197a8717320c0e887f2b2f6 (MD5) Previous issue date: 2016-09-22 / Introduction. The spondyloarthritis encomprises a group of diseases strongly associated with HLA-B*27 gene. It has been proposed that genes not belonging to the major histocompatibility complex human influence the genesis of these diseases especially in patients HLA-B*27 negative. Objectives. The aim of this study was to test the hypothesis that the antigens of the ABO, Secretor and Lewis histo-blood systems are associated with spondyloarthritis, especially ankylosing spondylitis (AS). Material and methods. Three hundred and ninety-four patients with clinical suspicion of spondyloarthritis sent for identification of HLA-B*27 gene were analyzed. One hundred and nineteen (30.2%) had confirmed the diagnosis of spondyloarthritis according to the ASAS criteria. The remaining 275 (69.8%) were used as controls. The identification of HLA-B*27 gene was performed using the PCR-SSOP method. The identification of the antigens of the ABO, Secretor and Lewis histo-blood systems was performed using hemagglutination and PCR-RFLP methods. The exact Fisher's test, the chi-square, and the values of Odds Ratio (OR) and Confidence Interval set at 95% were calculated using the GraphPad INSTAT software, accepting the error of 5%. Results. No statistically significant differences were observed in the frequency of antigenic profiles of ABO (χ2: 1.152; p = 0.764; GL: 3), Secreto (χ2: 0.779; p = 0.377; GL: 1) and Lewis (χ2: 1.853; p = 0.396; GL: 2) histo-blood groups between patients and controls. The Lea antigen was more frequent in patients with AS compared to controls (OR: 1.833; 95% CI: 1025- 3284, p = 0.053). This antigen was strongly associated with AS in HLA-B*27 negative patients compared to controls (OR: 4.469; 95% CI: 1931-10342; p = 0.0007). This association remained only in males in the absence of HLA-B*27 gene (OR: 6.880; 95% CI: 1852-25564; p = 0.004). Conclusions. AS is associated to the Lea antigen in HLAB* 27 negative male patients. / Introdução. As espondiloartrites compreendem um grupo de doenças fortemente associadas ao gene HLA-B*27. Tem sido proposto que genes não pertencentes ao complexo principal de histocompatibilidade humano influenciam a gênese destas doenças especialmente nos pacientes HLA-B*27 negativos. Objetivos. O objetivo deste estudo foi testar a hipótese de que os antígenos dos sistemas histo-sanguíneos ABO, Secretor e Lewis estão associados à espondiloartrites, especialmente a espondilite anquilosante (EA). Material e método. Foram analisados 394 pacientes com suspeita clínica de espondiloartrites encaminhados para identificação do gene HLA-B*27. Cento e dezenove (30,2%) tiveram o diagnóstico de espondiloartrite confirmado de acordo com os critérios ASAS. Os 275 (69,8%) restantes compuseram o grupo controle. A identificação do gene HLA-B*27 foi realizada com o uso do método PCR-SSOP. A caracterização dos antígenos dos sistemas histo-sanguíneos ABO, Secretor e Lewis foi realizada com o uso dos métodos hemaglutinação e PCR-RFLP. O teste exato de Fisher, o qui-quadrado, os valores de Odds Ratio (OR) e do intervalo de confiança a 95% foram calculados com o uso do software GraphPad Instat, aceitando o erro de 5%. Resultados. Não foram observadas diferenças estatisticamente significantes nas frequências dos perfis antigênicos dos sistemas histo-sanguíneos ABO (χ2: 1.152; p=0,764; GL: 3), Secretor (χ2: 0.779; p=0,377; GL: 1) e Lewis (χ2: 1.853; p=0,396; GL: 2) de pacientes e controles. Foi observada maior frequência do antígeno Lea em pacientes com EA, comparados aos controles (OR: 1.833; IC 95%: 1.025 – 3.284; p=0,053). Este antígeno mostrou-se fortemente associado à EA em pacientes HLA-B*27 negativos comparados aos controles (OR: 4.469; IC 95%: 1.931 – 10.342; p=0,0007). Esta associação se manteve apenas no gênero masculino na ausência do gene HLA-B*27 (OR: 6.880; IC 95%: 1.852 – 25.564; p = 0,004). Conclusões. A EA está associada ao antígeno Lea nos pacientes masculinos HLA-B*27 negativos.

A research report submitted to the faculty of Medicine, University of the Witwatersrand, Johannesburg, in part fulfillment of the requirements for the degree of Master of Medicine (in the branch of Haematology) Johannesburg 1992. / The observation by Haldane in 1949 that the distribution of malaria and certain thalassaemias were similar and that the former disease must be a selective force tor the continued existence of the latter by preservation of the heterozygotes. This theory which later became known as lithe malaria hypothesis" has been applied to other inherited conditions such as G6PD deficiency, membranopathies, certain blood group polymorphisms, other heamoglobinopathies such as sickle cell disease, blood group polymorphisms and more recently HLA phenotypes. It has been shown that the Duffy blood group antigens are the receptors for. Plasmodium vivax and since these antigens are lacking in most black Africans this species of malaria is virtually absent in Africa. It has also been shown that the glycophorins are at least in part the receptors for Pfalciparum. Several variants of the glycophorins exist and the biochemistry and, where known, the molecular mechanisms by which these arise is reviewed. Experimental work is carried out to establish the growth characteristics of Pfalciparum in an in vitro culture system using cells with glycophorin variants on their membranes. Three such variants were compared to normal cells and two (S~s-U-and Dantu) were found to be partially resistant to invasion by Pfalciparum merozoites whereas the third (Henshaw) was found to be no different to controls. / MT2018

Glycosyltransferase enzymes synthesize glycosidic linkages, generating carbohydrates and carbohydrate-linked entities ranging from cellulose, starch, and chitin to glycolipids, glycopeptides, and natural product antibiotics. These syntheses involve stereo- and regio-specific sugar transfer from an activated donor molecule, often a UDP-sugar, to an acceptor molecule. Functionally, glycosyltransferases are classified as either “retaining” or “inverting” enzymes depending on whether the stereochemical linkage of the donor substrate is conserved in the product. While inverting glycosyltransfer is mechanistically straightforward, the retaining mechanism remains poorly understood. For retaining glycosyltransferases, the central question is whether transfer occurs via a front-face “SNi-like” mechanism or through a ‘double displacement’ mechanism that invokes a glycosyl-enzyme covalent intermediate. GTA and GTB are retaining enzymes that catalyze the final step in human ABO(H) blood group A and B antigen synthesis through UDP-GalNAc or UDP-Gal transfer, respectively, to the H-antigen disaccharide acceptor. Although they have been intensively characterized, the processes of substrate recognition, mobile loop organization, and product release in GTA and GTB has long resisted explanation. Further, the question of the retaining enzyme mechanism persists, though the covalent intermediate of the proposed double displacement mechanism has been detected via mass spectrometry experiments with GTA/GTB mutants. Building on previous investigations, we have aimed to characterize and have uncovered details of mechanism, substrate binding, loop organization, and product release using a combined kinetic and structural approach. These investigations are essential not only for understanding GTA, GTB, and retaining glycosyltransferases as a whole, but also for the rational design of inhibitors. Such inhibitors could selectively target, for example, bacterial glycosyltransferases and thus would represent a new class of antimicrobials. / Graduate

Being among the most prevalent of persistent infectious agents in humans worldwide, Helicobacter pylori induces chronic inflammation (gastritis), which may progress to peptic ulceration and stomach cancer. The ability to adhere to the gastric mucosa is considered to be both a colonization and virulence property of H. pylori. For adherence, H. pylori expresses surface-located attachment proteins (adhesins) that bind to specific receptors in the gastric mucosa. The best characterized H. pylori adhesin-receptor interaction is that between the blood group antigen binding adhesin (BabA) and the fucosylated blood group antigens, which are glycans highly expressed in the gastric mucosa. Our recent results have changed the view of the blood group antigen-specific binding mode of H. pylori. We have tested clinical isolates of H. pylori from human populations worldwide for their ability to bind to ABO blood group antigens. The results revealed that more than 95% of isolates from Sweden, Germany, Spain, Japan and Alaska that bind fucosylated blood group antigens, bind both the Lewis b antigen (Leb) (of blood group O) and the blood group A-related antigen A-Lewis b, i.e. they exhibit a generalist type of binding mode. In contrast, the majority of strains (62%) from South American Amerindians bound best to Leb, i.e. they exhibit a specialist blood group “O antigen” binding mode. This specialization in binding coincides with the unique predominance of blood group O in the South American Amerindian populations. Furthermore, we also showed that H. pylori could switch from specialist to generalist binding modes by chromosomal integration of foreign babA gene fragments. A mutant strain lacking the babA gene turned out to adhere to inflamed gastric epithelium, despite the fact that it did not bind Leb. We identified the receptor to which the mutant binds to as the sialyl-dimeric-Lewis x antigen (sdiLex) and found its expression to be associated with persistent H. pylori infection and chronic inflammation, both in humans and Rhesus monkeys. The cognate sialic acid binding adhesin (SabA) was identified by our ReTagging technique. Deletion of sabA caused loss of H. pylori binding to sialylated glycans, and screening of single colony isolates revealed a high frequency of spontaneous on⇒off phase variation in sLex binding. Using erythrocytes as a model for sialyl dependent cell adhesion, we could show that SabA is the sought-after H. pylori sialyl-dependent hemagglutinin. Swedish clinical H. pylori isolates were analyzed for sialyl-dependent hemagglutination (sia-HA), and the sia-HA titers were found to be highly correlated to the levels of sLex binding. Clinical isolates were shown to exhibit several distinct binding modes for sialylated glycans, which suggest that SabA exhibit polymorphism in binding. We also found that SabA binds to sialylated glycans on neutrophil surfaces by mechanisms involving “selectin mimicry”, and that SabA plays an important role in nonopsonic activation of neutrophils. In the human stomach, H. pylori is exposed to selective pressures such as immune and inflammatory responses, and this is reflected by changes in mucosal glycosylation patterns. The high mutation and recombination rates of H. pylori in combination with bio selection will continuously generate clones that are adapted to changes in individual gastric mucosa. Such adaptive selection contributes to the remarkable diversity in binding modes and to the extraordinary chronicity of H. pylori infections worldwide.

In malaria endemic regions, resistance to malaria constitutes a critical selective pressureon genetic polymorphisms that regulate immune defense and inflammatory pathways.Differences in malaria susceptibility between sympatric ethnic groups have been described inMali. The Fulani are less susceptible to malaria compared to the neighboring group the Dogon,in spite of similar socio-economic and environmental conditions. Paper I is focused on IL-4-590 T/C polymorphism and correlation with levels of malariaspecific IgG, IgG (1-4) subclasses as well as malaria specific and total IgE level in the two ethnicgroups. Our data show that the Fulani individual carrying the IL-4-590 T allele found to havehigher parasite carriage rate and had higher levels of malaria-specific IgG4 and IgE compared tothe individual carrying the C allele. No such differences were seen within the Dogon.Paper II investigated 166 SNPs in the human host in individuals belonging to the Fulani and theDogon ethnic groups. These SNPs were correlated with total IgG against AMA-1, MSP-1, MSP-2 and CSP antigens as well as total IgE level. All antibody levels were higher in the Fulanicompared to the Dogon and strengthens previous finding that antibodies might play a role in theprotection seen in the Fulani. We identified higher frequencies of the protective blood group O.Several allelic differences between the two ethnic groups were found in CD36, IL-4, RTN3 andADCY9. Moreover several polymorphisms in SLC22A4, IRF1, IL5, LTA and TNF have beenfound to be correlated with anti-MSP antibody level; TLR6, IL3, TNF, and IL22 found to becorrelated with anti-MSP-2 antibody level in the Fulani. Such association was not seen in theDogon. In Paper III, the same individuals, as in paper II, were investigated with a focus on the FcγRIIapolymorphism and correlation with levels of anti-AMA-1, MSP-1, MSP-2, CSP specificantibodies as well as total IgE level. The genotype distribution and allele frequency weresignificantly different between the Fulani and the Dogon with the Fulani being HH, H allele- andthe Dogon RR, R allele carriers. A correlation between the HH genotype and the H allele andprotection against mild malaria was seen in the Fulani but not in the DogonTaken together our study has found significant genetic differences between the Fulani and theDogon Ethnic groups, which suggest that ethnicity should be taken into account in monitoring ofimmunological studies and vaccines trials in malaria endemic areas.

Thesis (M.P.H.)--University of Michigan, 1945.