Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis advisor: Jeffery A. Byers / Thesis advisor: Chia-Kuang Tsung / Host-guest chemistry provides a unique platform for catalysis by combining the specificity of homogeneous catalysts with the stability and recyclability of heterogeneous catalysts. Metal-Organic Frameworks (MOFs), such as UiO-66 are ideal hosts for host-guest catalysis. The vast porous network UiO-66 forms is chemically and thermally stable and the individual cages that make up the crystals can be modified by simple organic syntheses. The method developed in our group provides a mild, synthetically simple route for non-covalent organometallic guest encapsulation that decouples host synthesis from guest encapsulation. In this study, the so-called aperture opening encapsulation method is tested using an unstable class of iron-based carbon dioxide hydrogenation catalysts. The study results in launching an extensive investigation into the driving force behind aperture opening encapsulation with the goal of increasing guest loadings. Various methods to achieve this goal are explored including synthesizing novel UiO-66 linkers and taking advantage of factors such as columbic force. In conclusion, the information gained from a bigger picture examination of aperture opening encapsulation directly leads to guest loadings high enough to utilize useful characterization techniques. Accordingly, a standard protocol for characterization of iron catalysts encapsulated in UiO-66 is developed. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

The exact mechanism of pathogenesis of inflammatory bowel disease (IBD) is not yet clear. However, a key role for intestinal bacteria in the development and maintenance of IBD is now well-accepted and has led to extensive efforts to characterize IBD patients’ gut microbiota composition. Nonetheless, few studies have examined intestinal microbial composition and host interactions in pediatric treatment-naïve IBD subjects. Using a multi-omic approach, we analyzed the gut microbiota-host interactions at the mucosal- luminal interface from two distinct colonic regions in a pediatric treatment-naïve cohort of Crohn’s disease (CD), ulcerative colitis (UC) and non-IBD control individuals. CD patients displayed a significant decrease in bacterial richness in the distal colon, as compared to controls. Significant changes in the microbial composition at different taxonomic levels were observed in IBD patients relative to controls, especially in the distal colon. IBD patients had an increased abundance of hydrogen sulfide (H2S) producers, including Veillonella (g), Streptococcus (g) and Fusobacterium (g), and a decreased abundance of butyrate producers such as Blautia (g), Lachnospiraceae (f) and Ruminococcus (g). IBD patients showed statistical differences in their metabolomic profile as compared to controls, with the majority of significant metabolites, such as pesticides, amino acids, bacterial-derived molecules and dipeptides, being increased in CD and UC subjects. An alteration of the gut microbiota composition was associated with an alteration of the host and bacteria metabolome in IBD subjects; notably, increase of taurine, mecarbam-f7 and oxazole positively correlated with H2S producers and negatively correlated with butyrate producers. Finally, microbial genes involved in oxidative stress response, virulence, iron uptake, storage and metabolism were upregulated in the proximal colon of IBD patients. Our findings provide information about the host-microbiota interactions in the context of IBD. Understanding the relationships between the host and his intestinal microbes could help to develop therapeutic strategies to treat IBD.

Indiana University-Purdue University Indianapolis (IUPUI) / Flavocytochrome b558, the catalytic core of the phagocytic NADPH oxidase, mediates the transfer of electrons from NADPH to molecular oxygen to generate superoxide for host defense. Flavocytochrome b is a membrane heterodimer consisting of a large subunit gp91phox (NOX2) and a smaller subunit, p22phox. Localization of flavocytochrome b to the phagosome is essential for microbial killing, yet the subcellular distribution of flavocytochrome b in macrophages and how it is incorporated into macrophage phagosomes is not well characterized. In neutrophils, flavocytochrome b localizes primarily to specific granules that are rapidly mobilized to the phagosome upon stimulation. In contrast to neutrophils, macrophages do not contain specific granules, and trafficking of membrane proteins to the phagosome is more dynamic, involving fission and fusion events with endosomal compartments. We hypothesized that in macrophages, flavocytochrome b localizes to both plasma membrane and endosomal compartments that deliver flavocytochrome b to the phagosome. We generated fluorescently tagged versions of both p22phox and gp91phox, and rigorously verified their functionality in Chinese Hamster Ovary cells. Localization of flavocytochrome b was then examined in both RAW 264.7 murine macrophages and primary murine bone marrow derived macrophages (BMDM) in the presence and absence of interferon gamma (IFNg). We found that in “resting” macrophages, flavocytochrome b localizes primarily to the Rab11-positive endosome recycling compartment that recycles to the plasma membrane. In addition, phagocytosis assays showed flavocytochrome b is incorporated into the phagocytic cup and colocalized with Rab11 at the base of the cup, suggesting Rab11-positive endosomes may be involved in trafficking of flavocytochrome b between intracellular membranes and forming or nascent phagosomes. However, in IFNg activated macrophages, flavocytochrome b was localized predominantly in the plasma membrane, with little present in endosomal compartments. This shift in flavocytochrome b distribution occurred following sustained exposure to IFNg and correlated with increased flavocytochrome b protein expression and increased extracellular production of superoxide. Taken together, our results suggest the IFNg-induced redistribution of flavocytochrome b may be important for enhancing the production of superoxide at the cell surface and may be a potential new mechanism by which IFNg enhances antimicrobial activity in macrophages.

Thesis / Master of Science (MS)

Hematopoietic stem cell transplant was developed as a curative therapy to treat onco-hematological diseases and recently indications for this therapy have expanded to include solid tumors, hemoglobinopathies and other genetic diseases and disorders. Two major types of hematopoietic stem cell transplant have been developed. Autologous transplants aim to deliver a massive dose of radiation and/or chemotherapy that is capable of ablating the hematopoietic stem cells in the bone marrow. The patient is then "rescued" from this lethal dose of treatment by an infusion of their own hematopoietic stem cells. Allogeneic transplants are designed to either functionally replace a cell class, or an enzyme or biological function absent in the patient, or to consolidate a remission in a onco-hematological disease via the graft-versus-tumor effect . Two of the largest causes of non-relapse mortality from an allogeneic hematopoietic stem cell transplant are acute and chronic graft-versus-host disease, in which immune cells derived from the graft recognize normal host tissue as foreign and attack these tissues. A host of biomarkers for acute graft versus host disease have been identified, but there is almost none for chronic graft versus host disease. Herein, a methodology to discover and validate a biomarker(s) for the most common organ system affected by chronic graft versus host disease is proposed.

Petri dish and olfactometer tests demonstrated that Goniozus natalensis (Gordh) females exhibit a host-searching response upon contact and at a short distance by olfaction, to a kairomone in the frass of its natural host Eldana saccharina (Walker). The host-searching response was found to be elicited by E. saccharina frass from a range of substrates, namely: two host plants of E. saccharina, papyrus and sugarcane, and four media: sugarcane, papyrus, and cellulose based media and a synthetic medium containing no plant material. The host-searching response was not elicited by Sesamia calamistis (Hamps) sugarcane medium frass. The sexual state and age of G. natalensis females were found to influence the host-searching behaviour. Mated females showed the behaviour in the petri dish bioassays only after completing their preoviposition time of two to three days, whilst virgin females took longer, even though their preoviposition time was found to be the same. The response to male or female produced E. saccharina sugarcane frass was not statistically different, nor was there a statistically significant preference for either frass type, given the choice. Four way olfactometer tests showed that an E. saccharina sugarcane frass odour elicited a host-searching behaviour in mated two to three day old G. natalensis females. Various solvents were tested for their ability to isolate the kairomone from E. saccharina sugarcane frass. Chloroform proved to be the best solvent when tested in petri dish and olfactometer bioassays. The preliminary results of the GC/MS analysis of the chloroform extract of E. saccharina sugarcane frass are presented. The chemicals identified are compared with chemicals identified as host location kairomones for other insect parasitoid-host studies. / Thesis (M.Sc.)-University of Natal, 1990.

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The aim of this study was to develop a sensitive and specific method of detecting Toxoplasma gondii in the immunocompromised host which would reduce the need for other tests and would ensure the prompt initiation of the appropriate treatment, the effects of which could be monitored. Such a system would also be of benefit in theinvestigation of parasite/host interaction. Initial work investigated an antigen ELISA and the PCR using two different gene targets CB 1 and P30) to find the most sensitive system. The ELISA was insensitive but both PCR systems were capable of detecting parasite in blood, lymph and tissue samples from experimentally infected sheep. The B 1 PCR detected parasite earlier and over a significantly longer period than the P30 PCR, this greater sensitivity being due to the higher copy number of the B 1 gene. The PCR was applied to samples from patients with AIDS with the aim of finding an ideal sample for the diagnosis of infection. Parasite was detected in blood up to a month prior to clinical signs of infection, and therefore blood samples are ideal for monitoringpatients at risk of recrudescence of a chronic infection. This result indicates that recrudescence is not due to local reactivation, but is due to a more widespread parasitaemia. However, as parasitaemia was shown to be transient in cases of recrudescence, sampling time may be critical. Parasite was also detected in urine, biopsytissue and post mortem material, but was not detected in CSF.Dexamethasone was used to create a mouse model of recrudescence in the immunocompromised patient to further investigate interaction between the parasite and host. The PCR detected parasite in blood, brain and heart of chronically infected animals, however the detection rate was significantly higher in groups receiveing immunosuppressive therapy. Dexamethasone treatment mimicked the effects seen in the AIDS population where 30-35% of chronically infected individuals showed clinical signsof toxoplasmosis. However the PCR may also be detecting latent cysts in tissue samples, and blood samples were occasionally positive without clinical evidence of infection. This could be due to small amounts of parasite circulating intermittently, or to breakdownproducts from parasite degradation. There was therefore a need to differentiate between active and chronic infection, and this was carried out by developing a quantitative PCR based on competitive amplification. A novel Sma I restriction site was created within the P30 gene, and known amounts were co-amplified with samples. The amplified products were then digested with Sma I to differentiate between mutated and T. gondii DNA and the point at which product yield was equalled indicated the amount of original DNA present in the sample. The system was shown to work using human PM samples, and could be adapted to indicate a cut-off point where parasite DNA levels reveal active infection. In conclusion the B 1 PCR is the method of choice in detecting T. gondii in AIDS patients. Any patient in which active parasite is detected should be treated and closely monitored using the qPCR for any evidence of reactivation.