<p>Malaria is the most common parasitic disease of humans worldwide. A factor that aggravates the many attempts to control the epidemiologic malaria situation is the spreading of resistance against anti-malarial drugs. In this project the point mutation at position 86 of the <em>Plasmodium. </em><em>falciparum</em><em> </em>multidrug resistance gene (<em>pfmdr1</em>), which is thought to contribute to Chloroquine resistance, was analysed in 188 samples from a low transmission area in eastern Sudan, where malaria endemicity is seasonal. The patient group studied had asymptomatic and sub patent parasitemia that persisted during the transmission-free dry season, after being treated with Chloroquine. To differentiate between wild type and mutant genotypes, nested PCR and restriction fragment length polymorphism with the enzyme Apo1 was used. Out of 188 samples 79 (42%) were successfully analysed. Of those, 72% had parasites with mutant genotypes or where mixed infection. No conclusions on the relevance of the <em>pfmd</em><em>r</em><em>1</em> gene in the studied samples are made due to the many remaining gaps. However, eventual sources of error and previous findings in the study area are discussed.</p>

<p>Invasive Candida infection is an increasing cause of morbidity and mortality in the immunocompromised patient. Molecular diagnosis based on genomic amplification methods, such as real time PCR, has been reported as an alternative to conventional culture for early detection of invasive candidiasis. The template DNA extraction step has been the major limitation in most reported nucleic acid based assays, due to problems in breaking fungal cell walls and incomplete purification in PCR inhibitor substances.</p><p>The aim of this study was to compare enzymatic cell wall disruption using recombinant lyticase with mechanical disruption using glass beads. The QIAamp tissue kit was compared with two automated DNA extraction robots, the BioRobot M48 and NucliSens easyMAG, to determine their sensitivity, reliability and duration for DNA release of C. albicans. Mechanical cell wall disruption shortened and facilitated the extraction procedure, but the quantity of released DNA was significantly lower than when enzymatic cell wall disruption was used. Use of robots did not significantly shorten the DNA extraction time, compared with manual DNA extraction. However the NucliSens easyMAG resulted in a higher yield of target DNA compared to the BioRobot M48 and the manual QIAamp tissue kit.</p> / <p>Invasiva svampinfektioner är ett stort problem hos patienter med dåligt immunförsvar. Förekomst av invasiva svampinfektioner har ökat under senare år och medför hög dödlighet. En svampinfektion som inte snabbt diagnostiseras och behandlas kan bli livshotande om patientens kondition är dålig. Candida albicans är den vanligaste orsaken till invasiva svampinfektioner. Med traditionell svampidentifiering kan det ta dagar till veckor att isolera och artbestämma svampen. En snabbare metod att detektera Candida är att använda sig av molekylärbiologiska metoder som påvisar svampens arvsmassa, DNA. Svampar har en cellvägg som är svår att bryta ner och därför är DNA extraktionssteget ett av de mest rapporterade problemen vid DNA svampdiagnostik.</p><p>Syftet med denna studie var att jämföra enzymatisk och mekanisk cellväggsnedbrytning av C. albicans med hjälp av enzymet lyticase respektive glaskulor. Vi jämförde också en manuell metod med två automatiska robotar för att bestämma deras känslighet, tillförlitlighet och tidsåtgång för DNA-extraktion från C. albicans. De slutsatser som nåtts är att den enzymatiska cellväggsnedbrytningen var känsligare men betydligt mer tidskrävande än den mekaniska cellväggsnedbrytningen. Denna studie visade även att en av de automatiska systemen extraherade signifikant mer DNA än den manuella metoden.</p>

The ability of human polymorphonuclear leukocytes (PMNL; neutrophils), to sense and move to sites of infection is essential for our defense against pathogens. Cell motility is critically dependent on a dynamic remodeling of morphology. The morphological polarization toward chemoattractants, such as N-formyl-Met-Leu-Phe (fMLF), is associated with temporary extension and stabilization of lamellipodia in the direction of movement. The underlying mechanisms of cell motility are, however, still not entirely elucidated. It is therefore an urgent task to extend the present experimental evidence to give solid basis for a comprehensive model. Here it is shown that nitric oxide (NO) stimulates the morphological response of neutrophils, most likely due to transient increases in [Ca2+]i, following addition of NO-donors. This will, hypothetically, activate gelsolin and other actin filament severing proteins, leading to a subsequent decrease in filamentous actin. The incapability to efficiently turnover the actin filament network then blocks all motile activity. It is also shown that N-formyl peptide receptors on polarized neutrophils accumulate non-uniformly towards regions involved in motility. It is suggested that neutrophils use the asymmetric receptor distribution for directional sensing and sustained migration. A model for lamellipodium extension, where water fluxes play a pivotal role is presented. It is suggested that water fluxes through water-selective aquaporin (AQP) channels, contribute to the propulsive force for formation of various membrane protrusions and, thus, cell motility. It is well known that small G proteins of the Rho family GTPases play important roles in the intracellular signaling underlying cell motility. In morphologically polarized neutrophils it is shown that Cdc42, Rac2 and RhoA display spatially distinct distributions, which allows for sequential chemoattractant stimulation of neutrophil motility. The specific localizations of Rac2, Cdc42 and RhoA relative to each other and filamentous actin and fMLF receptors support the hypothesized order of activation and regulation of neutrophil cell motility. In conclusion, the detailed analysis of motility-related issues presented here provide new data allowing further refinement of previous models of neutrophil motility.

Apoptosis, or programmed cell death, is a controlled process by which aged or damages cells are eliminated in multicellular organisms. Neutrophils, short-lived phagocytes of the innate immune system, are highly equipped effectors that can sense, locate, ingest and kill bacterial pathogens. Inflammatory mediators and the presence of bacterial products at the foci of infection regulate the function and life span of these cells. Modulation of neutrophil apoptosis and the subsequent clearance by scavenger cells, such as macrophages, is part of a balanced inflammatory process leading to resolution of inflammation. Many pathogens are capable of modulating host cell apoptosis, and thereby influence the progression of disease. Hence, this thesis was aiming at elucidating mechanisms involved in pathogen- and host-modulated apoptosis and its contribution to the inflammatory process. We found that different routes of bacterial entry, i.e. through invasion or by receptor-mediated phagocytosis, triggered different signaling pathways within phagocytes. Invasion of virulent Salmonella caused apoptosis, a process requiring activation of the Rho GTPases Rac1 and Cdc42. On the other hand, phagocytosis of the non-invasive Salmonella inhibited apoptosis despite similar intracellular survival as the invasive bacteria. Protection against phagocytosis-induced apoptosis was regulated by tyrosine- and PI3-kinase-dependent activation of AKT (also called PKB for protein kinase B). Furthermore, inhibiting the intraphagosomal production of reactive oxygen species (ROS) in neutrophils during phagocytosis of E. coli decreased apoptosis below spontaneous apoptosis, further indicating that both pro- and anti-apoptotic pathways are triggered by receptor-mediated phagocytosis. Type 1 fimbria-expressing E. coli adhering to neutrophils resisted ingestion, and induced a ROS-dependent apoptosis by a cooperative effect of the FimH adhesin and LPS. To explore how compartmentalization of ROS during neutrophil activation was involved in modulating apoptosis, we evaluated the stability of lysosomes. In contrast to phagocytosis of E. coli, the adhesive strain induced intracellular non-phagosomal ROS production which triggered early permeabilization and release of lysosomal enzymes to the cytosol. Cathepsin B and/or L were responsible for targeting of the pro-apoptotic Bcl-2 protein Bid, thereby inducing mitochondrial damage, and apoptosis. These data propose a novel pathway for ROS-induced apoptosis in human neutrophils, where the location of the ROS rather than production per se is important. Moreover, we found that pathogen-induced apoptotic neutrophils, in contrast to uninfected apoptotic neutrophils, activated blood-monocyte derived macrophages to increase their FcγRI surface expression and to produce large quantities of the pro-inflammatory cytokine TNF-α. This demonstrates that during the early phase of infection, pathogen-induced neutrophil apoptosis will help local macrophages to gain control over the microbes. Furthermore, we suggest that heat shock protein 60 and 70 represent a stress signal that enables macrophages to distinguish between, and react differently to, uninfected and inflammatory apoptotic neutrophils.

Celiaki, eller glutenintolerans, är en av våra vanligaste kroniska sjukdomar i barnaåren. Sjukdomen orsakar en kraftig inflammation i tunntarmens slemhinna efter intag av glutenhaltig föda hos personer med ärftlig benägenhet att utveckla celiaki. En frisk tarm är kraftigt veckad för att öka ytan för upptag av näringsämnen. Ytan består dessutom av åtskilliga fingerliknande utskott, s.k. villi, och mellan villi finns kryptorna där celldelning och celldifferentiering sker. Villi och kryptor kantas av epitelceller, enterocyter, vilkas uppgift är att ta upp näring från tarminnehållet samt att utgöra en selektiv barriär mellan den yttre och inre miljön i tarmen. Den typiska tarmskadan vid celiaki karakteriseras av avsaknad av villi och kraftigt förlängda kryptor, och både näringsupptaget och barriärfunktionen är dessutom störda. Den enda behandling som finns att tillgå vid celiaki är en livslång glutenfri diet. De skadliga proteinerna i vetegluten kallas gliadin, och det finns liknande proteiner i råg, korn, och havre. I havre kallas proteinet avenin. Möjligheten att använda havre vid celiaki har diskuterats flitigt, men numera anses det riskfritt för majoriteten av både barn och vuxna att använda havre i den glutenfria dieten. Målet med den här avhandlingen var att undersöka hur barn med celiaki reagerar på havre i kosten. Detta studerades med avseende på antikroppar mot avenin samt med en metod som mäter halten av kväveoxid- (NO-) produkter i urinen. Ett andra mål var att studera tunntarmens struktur vid olika stadier av celiaki. I den första studien undersökte vi om celiakibarn har antikroppar i serum mot avenin. Vi fann att så var fallet och att nivåerna var signifikant högre än hos friska kontrollbarn. När barnen sattes på glutenfri kost sjönk antikroppsnivåerna, för att öka igen när gluten återinfördes i kosten. Blodproverna till den här studien togs innan debatten om havre kom igång, vilket gör att vi tror att de olika dieterna även speglar ett sant intag av havre. Studien visade också att det inte var någon korsreaktion mellan antikroppar mot avenin och gliadin. Vi använde sedan vår metod för att mäta antikroppar mot avenin i en randomiserad studie där havre gavs till barn med nydiagnostiserad celiaki. Barnen fick antingen en vanlig glutenfri diet eller en med tillsats av specialhavre. Antikroppsnivåerna sjönk markant redan efter tre månader i båda grupperna, och vid studietidens slut, efter ca ett år, hade alla utom ett par patienter återfått normala nivåer. Samma barn studerades även med avseende på NO-produkter i urinen. NO är en kortlivad molekyl som fungerar som budbärare i och mellan celler, och produktionen av den ökar markant vid en inflammation. Tidigare studier har visat att barn med obehandlad celiaki har extremt höga halter av NO-produkter i urinen. I vår studie sjönk även dessa värden signifikant efter tre månader, och det var ingen skillnad mellan grupperna. Efter ett år hade dock fyra barn i havregruppen och ett barn i den grupp som fick vanlig glutenfri kost, fortfarande extremt höga nivåer av NO-produkter. Dessa båda studier styrker den kliniska uppfattningen att de flesta barn med celiaki kan tåla havre, men de visar också att man bör följa upp de celiakibarn som kompletterar sin glutenfria kost med havre eftersom vissa barn verkar ha kvarstående tecken på inflammation i tarmen. I tarmbiopsier från barn med olika stadier av celiaki studerades förekomst och lokalisering av occludin och claudiner, proteiner som är viktiga för att upprätthålla barriärfunktionen i tarmen. Vi fann ett ökat uttryck av occludin vid obehandlad celiaki, vilket vi tror speglar den ökade celldelning och de förändrade barriäregenskaper som man ser vid aktiv celiaki. Resultaten tyder även på att uttrycket av claudin 1-5 inte tycks påverkas av kosten hos barn med celiaki. / Coeliac disease (CD) is one of our most common chronic diseases in childhood. The disease causes an intense inflammation in the small intestinal mucosa after ingestion of gluten-containing cereals in genetically predisposed individuals. The mucosal lesion in CD is characterised by villous atrophy and crypt hyperplasia, and both the absorptive and the barrier functions of the enterocytes are disturbed. The treatment of CD is a life-long adherence to a gluten-free diet (GFD). The toxic fraction of wheat gluten is gliadin, and there are similar proteins in rye, barley and oats. In oats this protein is called avenin, and it is proposed to be less toxic than the others. The use of oats in CD has been debated, but it is now considered safe for the majority of both children and adults with CD. The aims of this thesis were to investigate the humoral and inflammatory reactions to oats in children with CD, and also to study the intestinal mucosa at different stages of the disease. In a retrospective study we found that children with CD had antibodies to oats avenin, and that the levels were significantly higher than in controls. The levels attenuated during GFD, and we also showed that there was no crossreactivity between antibodies to oats and gliadin. We then used our method for measuring antibodies to avenin in a randomised, double-blind trial of oats given to children with newly diagnosed CD. The children were given either a traditional GFD or a GFD supplemented with oats. There was a rapid decrease in antibody levels in both groups already after three months on diet, and at the end of the study period all but a few had normalised their levels. The same children were also studied using urinary nitric oxide (NO) products as markers for intestinal inflammation. Likewise, these values decreased significantly after three months. At the end of the study four children in the GFD-oats group and one in the standard GFD group still had extremely high concentrations of urinary NO metabolites. Taken together, these studies strengthen the clinical impression that oats can be tolerated by the majority of children with CD, but they also warrant a caution, since there seem to be children that do not tolerate oats in their diet. The structure and distribution of occludin and claudins 1-5, tight junction proteins known to play a crucial role in maintaining the barrier function, was studied in biopsy specimens from children at different stages of CD. There was an increased expression of occludin in untreated CD, which reflects the characteristics of crypt cell hyperplasia and altered barrier properties seen in active CD. The findings also indicate that gluten intake does not significantly influence the expression and distribution of claudins 1-5 in coeliac children.

Relapsing fever (RF) is a disease caused by tick- or louse-transmitted bacteria of the genus Borrelia. It occurs worldwide but is most common in Africa where it is one of the most prevalent bacterial diseases. The main manifestation is a recurring fever which coincides with massive numbers of bacteria in the blood. Severity ranges from asymptomatic to fatal. RF is usually considered a transient disease. In contrast, B. duttonii causes a persistent, residual brain infection in C57BL/6 mice which remains long time after the bacteria are cleared from the blood. The host gene expression pattern is indistinguishable from that of uninfected animals, indicating that persistent bacteria are not recognized by the immune system nor do they cause noticeable tissue damage. This is probably due to the quite low number of bacteria residing in the brain. The silent infection can be reactivated by immunosuppression allowing bacteria to re-enter the blood. To investigate if the residual infection is in a quiescent state or if the bacteria are actively dividing, mice with residual brain infection were treated with the cell-wall disrupting antibiotic ceftriaxone, which is only active against dividing bacteria. Since all mice were cured by ceftriaxone we conclude that the bacteria are actively growing in the brain rather than being in a latent, dormant state. The brain is used as an immunoprivileged site to escape host immune defence and probably as a reservoir for bacteria. RF is a common cause of pregnancy complications, miscarriage and neonatal death in sub-Saharan Africa. We established a murine model of gestational relapsing fever to study the pathological development of these complications. B. duttonii infection during pregnancy results in intrauterine growth retardation as well as placental damage and inflammation. Spirochetes cross the maternal-foetal barrier, resulting in congenital infection. Further, pregnancy has a protective effect, resulting in milder disease during pregnancy. A clinic-based study to investigate the presence of RF in Togo was performed. Blood from patients with fever were examined for RF by microscopy, GlpQ ELISA and PCR. About 10% of the patients were positive by PCR and 13% had antibodies to GlpQ. Many RF patients originally had a misdiagnosis of malaria, which resulted in ineffective treatment. The inability of microscopic analysis to detect spirochetes demonstrates the need for tests with greater sensitivity. To provide simple, fast, cheap and sensitive diagnostics using equipment available in small health centres, a method based on enrichment of bacteria by centrifugation and detection by Giemsa staining was developed which detects <10 spirochetes/ml. To study the phylogeny of RF, IGS and glpQ were sequenced and neighbor joining trees were constructed. B. persica and B. hispanica were distant from the other species iswhereas B. crocidurae appeared to be a heterogeneous species. B. duttonii is polyphyletic in relation to B. recurrentis suggesting that the two species may in fact be the same or have a polyphyletic origin.

Borrelia burgdorferi is a pathogenic spirochete which cycles between its arthropod vector and vertebrate host. If transmitted to humans, B. burgdorferi causes Lyme disease, an infection which can impair different organs, such as the skin, joints, nervous system and heart. Alterations in protein expression due to the different environments Borrelia encounters during its complicated life cycle require advanced adaptation mechanisms. The outer surface-exposed proteins play a critical role in survival and pathogenesis of Borrelia in different hosts and tissues, being involved in avoiding the host immune response, adhesion to different tissues and nutrient acquisition. This thesis aimed to characterize integral outer membrane proteins which play a role in solute and nutrient uptake, and provides support for their role in the environmental adaptation of Borrelia. In this thesis, three B. burgdorferi proteins, P13, BBA01 and P66, were shown to be porins, and characterized structurally and functionally using a combination of biochemical, biophysical and genetic methods. The channel-forming function of the 13 kDa protein, P13, was elucidated by a lipid bilayer assay. Post-translational processing of P13 occurred at the C-terminus by C-terminal processing protease (CtpA)-dependent cleavage. The membrane-spanning architecture of P13 was determined by epitope mapping and computer-based structural predictions which revealed that P13 is an unusual porin, not possessing the structural properties of conventional porins: rather than forming β-barrels, it is predicted to span the membrane with hydrophobic α-helices. p13 belongs to a paralogous gene family. The transcription of p13 and other gene family members during in vitro growth and in a mouse infection model was therefore investigated. The paralog BBA01, which has the highest sequence homology to P13, is expressed during in vitro growth in all three Lyme disease causing species, although at very low levels. Like P13, BBA01 is also processed by CtpA and exhibits very similar channel-forming activity. Furthermore, in the absence of P13, a proportion of total BBA01 protein is relocated to the bacterial surface with strong indications that BBA01 and P13 are functionally interchangeable. P66, an integrin binding protein, was also determined to be a porin. The oligomeric state of native P66, elucidated by chemical cross-linking, indicated that P66 forms trimers, as do the majority of conventional porins. Electron crystallography and a projection map of P66 crystals at 2.2 nm resolution revealed tetragonal unit cell symmetry with the area intercalated between the assembled protein structures consistent with the approximate expected size of the channel formed by P66. Finally, the biological relevance of two porins, P13 and P66, was demonstrated in a double mutant displaying a stress response as revealed by increased sensitivity to high osmolarity and elevated expression of the B. burgdorferi heat-shock protein HtrA homolog.

<p>Allergic diseases, for example asthma and eczema, are nowadays considered belonging to the most common chronic diseases amongst children in the West, but the cause for this increase in allergy prevalence is unknown. Since studies have indicated a connection between children's exposure of microorganisms during infancy and risk of developing allergic disease, it is suggested that this exposure is a crucial factor in question of allergy development or not. Other studies have established differences in microflora composition between healthy children and children with allergic disease, and several studies have shown that probiotic therapy can give positive results in both prevention and treatment of allergic diseases.</p><p>The aim of this master's thesis was to develop a method, using PCR and denaturing gradient gel electrophoresis, to study the diversity of <em>Lactobacillus spp</em>. in fecal samples retrieved from a study of the probiotic strain<em> L. reuteri</em> ATCC 55730. The developed method was successful in detecting lactobacilli in fecal samples, but three other bacterial genera commonly found in humans were also amplified. Comparison of average numbers of detected bacterial strains and lactobacilli strains between samples belonging to the probiotics and placebo groups, respectively, showed higher numbers for the probiotics group. Also, the only fecal samples that contained <em>L. reuteri</em> belonged to the probiotics group. Although the results are far from statistically significant, they support the theories that probiotics may influence the intestinal microbiota.</p>

The main causative agent of human urinary tract infections is the uropathogenic Escherichia coli (UPEC) pathotype. It may cause disease due to its ability to express a number of bacterial virulence factors. Fimbrial adhesins are particularly important for the initial establishment of infection in the urinary tract. The fimbriae are hair-like structures protruding from the bacterial cell and by attaching to specific receptors in the urinary tract they mediate adherence to different cell types, allowing the bacteria to resist the shear forces from urine flow. The UPEC strains generally carry multiple determinants for fimbrial adhesins. Previous studies have indicated that there is a co-regulation between different fimbrial genes and one factor that has been implicated in this is the PapB protein, acting as a transcriptional regulator of P-fimbrial expression. The PapB protein can be regarded as the prototype of a family of fimbrial regulators that show high homology between different fimbrial operons. One homolog is FocB, regulator of F1C fimbriae. In this study, the role of the FocB protein in the regulation of F1C fimbriae as well as in the co-regulation with other fimbrial genes was investigated. It was observed that FocB binds to DNA, similarly to PapB, in an oligomeric fashion and that PapB and FocB can form hetero-oligomeric complexes, which appear to have a repressive role in the regulation of the F1C fimbriae. In addition, the FocB protein also had a repressive effect on transcription of the fim operon, which encodes theType 1 fimbriae. For further analysis of FocB in vitro, we developed efficient procedures for purification of the protein and established conditions for its crystal formation with the aim to conduct X-ray diffraction studies. By the hanging-drop vapour-diffusion method, we obtained crystals that in the X-ray analysis diffracted sufficiently well to allow modelling of a high resolution structure of FocB. The structural model was considered in relation to the DNA binding properties of the protein. The FocB analysis represents the first structural model of this family of transcriptional factors. This model should aid in further understanding of the roles and functions of these proteins in the regulation of the UPEC fimbrial operons. The complexity of the system, with multiple factors involved in the regulation of fimbrial operons, was revealed in earlier studies of the PapI protein showing that PapI activates transcription of the pap operon as a part of a complex with the global regulator Lrp. However, PapI itself did not appear to bind to DNA and its mode of action has remained unclear. By genetic analyses and in vitro studies we show that PapI may interact also with the α subunit of the RNA polymerase. This finding indicates that PapI might directly interact with the transcriptional apparatus and thus aid in the activation of pap expression. Bacteria are frequently releasing outer membrane vesicles (OMVs) from their surface. We studied the release of the haemolysin toxin from E. coli in connection with formation of OMVs and found that the toxin was tightly associated with the vesicles in an active form. By overproduction of the PapB or PapI regulators in order to maximise the population of bacteria expressing fimbriae, we could detect P fimbriae proteins associated with OMVs that displayed specific adhesion to receptor-coated beads. This suggests a possible scenario in which the vesicles canfunction as directed vehicles of bacterial virulence factors.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 3 uppsatser.