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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

STUDY OF MOLECULAR INTERACTIONS OF GLYCOSAMINOGLYCANS AND GLYCOSAMINOGLYCAN MIMETICS WITH THEIR PROTEIN TARGETS

Afosah, Daniel K 01 January 2017 (has links)
Glycosaminoglycans (GAGs) are complex linear chain carbohydrate molecules found on virtually all animal cell surfaces. Owing to their negatively charged nature, GAGs interact with a number of different proteins. Thus, although they have great potential as therapeutic agents, their apparent promiscuous interactions increase their side effect risk. GAG mimetics, including GAG oligosaccharides and non-saccharide GAG mimetics (NSGMs) are viable approaches to address this. This work discusses sulfated benzofuran thrombin inhibitors with submaximal protease inhibition, sulfated diflavonoid inhibitors of plasmin and GAG oligosaccharides with selectivity for human neutrophil elastase (HNE). Anticoagulants are very important for the treatment of thrombotic diseases. The adverse effects associated with current clinically used anticoagulants warrant the continuous search for new agents. Thrombin, being the central player in the coagulation cascade, remains a very important target for anticoagulant therapy, however drugs inhibiting its activity carry the risk of prolonged bleeding. Based on a previously identified sulfated benzofuran thrombin inhibitor, we have developed analogs with submaximal inhibition of the protease. These agents inhibit thrombin with efficacies approaching 50%, for both chromogenic and macromolecular substrates, ensuring a basal level of thrombin activity even at saturating inhibitor concentrations. The most potent of these compounds had a potency of 1.8 µM, 2-3 fold better than the lead. Additionally, these compounds utilize an allosteric mechanism for thrombin inhibition. Further, studies have revealed structural features responsible for submaximal thrombin inhibition. Fibrinolysis is an important part of hemostasis and plasmin is the most important fibrinolytic enzyme. Anti-plasmin agents are thus important for conditions such as hemophilia; however, there are no clinically used direct plasmin inhibitors. By structural modifications of a previously identified sulfated diflavonoid plasmin inhibitor, we have achieved a compound with 12-fold better potency (IC50 = 6.3 ± 0.4 µM), and a selectivity index of at least 22 over closely related serine proteases. We have shown that this compound inhibits plasmin mediated clot lysis, and further demonstrated that its activity is reversible using protamine sulfate, indicating its potential as a lead for the development of clinical anti-plasmin agents. HNE, a serine protease associated with inflammatory diseases is known to be inhibited by GAGs. However, the interactions at the molecular level have remained elusive. Using biochemical methods, and by studying the inhibitory potency of different GAGs and GAG oligosaccharides, we have shown that an octasaccharide may be the ideal GAG length for the achievement of potent HNE inhibition. Under our assay conditions, the inhibition of HNE by an octasaccharide species was only 5-fold less than that of unfractionated heparin, whereas the hexasaccharide species was 30-fold less active. The data also suggests that the inhibition of HNE by GAGs is via an allosteric mechanism and using molecular modeling, we have identified putative GAG binding sites on HNE and further identified GAG species with potential selectivity for anti-HNE activity
22

Regulation of the Cellular Inhibitor of Apoptosis 1 (cIAP1) Translation by IRES Trans-Acting Factors and Impact on Cancer

Faye, Mame Daro January 2015 (has links)
Apoptosis is the mechanism by which complex multicellular organisms induce the programmed death of damaged cells, thus maintaining tissue homeostasis. One of the main hallmarks of cancer, apoptosis is tightly regulated by pro- and anti-apoptotic factors whose equilibrium will decide of the fate of the cell. Among these factors, the cellular inhibitor of apoptosis cIAP1 is a key regulator of nuclear factor-κB dependent signaling and of caspase-8 mediated apoptosis. cIAP1 expression is controlled primarily at the translational level through an internal ribosome entry site (IRES) that facilitates the recruitment of the ribosome to the translation initiation start independently of the 5’ cap. We have previously identified four putative IRES trans-acting factors (ITAFs) that bind specifically to the cIAP1 IRES, namely NF45, NF90, IGF2BP1 and RH1. My research project characterised NF45 as an ITAF that positively regulates the IRES-mediated translation of cIAP1 and of the Xlinked inhibitor of apoptosis, XIAP. This regulation is important for maintaining Survivin and Cyclin E protein levels and insuring proper cell division. Furthermore, I showed that IGF2BP1 is another ITAF that is overexpressed in rhabdomyosarcoma cancer (RMS) and positively regulates cIAP1 translation, thus leading to apoptotic resistance in these cells. Importantly, the use of Smac mimetics, chemical compounds that cause cIAP1 proteasomal degradation, induces TNFα-mediated apoptosis of RMS cells and leads to growth inhibition of RMS xenograft tumors as well as significantly improved survival. Finally, I show that certain modulators of innate immunity synergize with Smac mimetics to improve the killing of RMS cancer cells. Hence, cIAP1 translation regulation by NF45 and IGF2BP1 is highly important for maintaining proper functioning of the cell and dysregulation of these ITAFs can lead to carcinogenesis.
23

Phenotypical and Functional Characterization of Polarized Human Macrophages

Iqbal, Salma January 2015 (has links)
Macrophages can be polarized into M1 and M2 macrophages based on the composition of the milieu. Human macrophages have been poorly characterized. In this study, various macrophage subsets were generated by treating monocyte-derived macrophages (MDMs) with IFNγ (M1), IL-4 (M2a), LPS and IL-1β (M2b) or IL-10 (M2c) which were characterized with respect to their cell surface marker profile and functional profile in the context of cytokine production, susceptibility to HIV infection and apoptosis. Each polarization state demonstrated a unique cell surface marker profile and cytokine profile. In addition M1 macrophages were shown to produce IFNγ post TLR stimulation. Moreover, M1 macrophages were highly sensitive to apoptosis following Smac mimetic treatment. Furthermore, M2a and M2c macrophages were resistant to apoptosis, induced by PI3K blockage and IAPs degradation respectively, and at the same time supported productive HIV infection unlike the other macrophage subsets. These findings might lead to better understanding of HIV reservoir formation and be used to develop therapies to eradicate it.
24

Translating Japanese Onomatopoeia into Finnish in Literature: A Case Study

Vanninen, Kosti January 2020 (has links)
Japanese is a language rich in onomatopoeic and mimetic words, words that mimic sounds and other phenomena with their form. They are an integral part of the language and are used in nearly all situations, they also pose their own peculiar challenge to both learners and translators of Japanese. This study examines the Japanese onomatopoeic and mimetic words in the novel Sensei no kaban by Hiromi Kawakami, and their translations in its Finnish translation, to determine what techniques are most commonly used and why? As Finnish is also said to have a rich onomatopoeic and mimetic vocabulary, the frequency at which these terms are translated into equivalent onomatopoeic or mimetic words is also examined. The results show that the majority of the Japanese onomatopoeic and mimetic words, most of which function as adverbs, are translated as adverbs or verbs or they are completely omitted. Exactly a quarter of the examined cases have been translated using onomatopoeic or mimetic words, most of which are verbs.
25

Selective Induction of Cell Death by Smac Mimetics in Primary Human Proinflammatory and Anti-inflammatory Macrophage Subsets

Ali, Hamza 23 February 2021 (has links)
The inflammatory and anti-inflammatory macrophages have been implicated in many diseases including rheumatoid arthritis, inflammatory bowel disease and chronic rhinosinusitis. Recent studies suggest targeting macrophage function and activation may represent a potential target to treat these diseases. Herein, I investigated the effect of second mitochondria-derived activator of caspases (SMAC) mimetics (SMs), the inhibitors of apoptosis (IAPs) proteins, on the killing of normal human pro- and anti-inflammatory macrophage subsets. It has been shown that human monocytes are highly susceptible to the cytotoxic effects of SMs, however, differentiated macrophages (M0) develop resistance to the cytocidal abilities of SMs. Whether human macrophage subsets are also resistant to the cytotoxic effects of SM remains unknown. My results show that differentiation of M0 macrophages towards M1 state rendered them highly susceptible to SM-induced cell death, whereas M2a, M2b and M2c differentiated subsets were resistant, with M2c being the most resistant. SM-induced cell death in M1 macrophages was mediated by apoptosis as well as necroptosis and activated both extrinsic and intrinsic pathways of apoptosis. The susceptibility of M1 macrophages to SM-induced cell death was attributed to the IFN-𝛾-mediated polarization as JAK inhibitor reversed their susceptibility. In contrast, M2c and M0 macrophages experienced cell death through necroptosis pathway following simultaneous blockage of the IAPs pathways by SM-LCL161 and the caspase pathways by the pan-caspase inhibitors (zVAD.fmk). I investigated the molecular mechanism governing SM-induced cell death in M1 macrophages. My results show that in contrast to the cancer cell lines, SM-induced cell death in M1 macrophages is independent of endogenously produced TNF-⍺, the canonical and non- canonical NF-𝜅B pathways. The susceptibility of M1 macrophages to SM-induced cell death was found to be dependent on IFN-𝛾-mediated differentiation through the JAK-STAT pathway and subsequent activation of IRF-1. In addition, the selective cell death in SM-treated M1 macrophages is mediated by simultaneous degradation of cellular IAP-2 (cIAP-2) and RIPK-1/3 through the activation of mTORC signaling pathway. Overall, the results suggest that survival of human macrophages is critically linked to the activation of the IAPs pathways. Moreover, agents blocking cIAP-1/2, mTORC and IRF-1 can be exploited therapeutically to address inflammation-related diseases. These observations hold a promising therapeutic strategy to limit the activation of proinflammatory M1 macrophages and eventually controlling the M1-associated diseases.
26

The Effects of SOCS1 and SOCS3 Peptide Mimetics on Macrophage Phagocytosis of Malignant Cells

Madkhali, Tahirah M. 14 May 2019 (has links)
No description available.
27

Augmentation of anti-myeloma engineered T cells by pharmacological or genetic interventions / Augmentation of anti-myeloma T cells

Afsahi, Arya January 2023 (has links)
Multiple myeloma is an aggressive plasma cell cancer that consistently acquires multi-drug resistance and relapses despite initial treatment successes. Patients may go through greater than 10-lines of therapy, highlighting the need for more effective treatment options. Immunotherapies are the latest evolution in targeted cancer treatments, and thus far have displayed impressive results in several hematological cancers, including multiple myeloma. T cells possess robust anti-tumor functions which can be harnessed and refined for the treatment of cancers. Genetic engineering of T cells to express a chimeric antigen receptor (CAR) confers antigen-specific tumor-targeting, and adoptive transfer of patient-derived CAR-engineered T (CAR T) cells has been efficacious in relapsed/refractory multiple myeloma. Despite the high efficacy, CAR T cell therapy for myeloma is associated with serious adverse events, which limits dose levels and patient eligibility. We have developed a novel synthetic antigen receptor platform, called the T cell antigen coupler (TAC) receptor, which has shown comparatively higher efficacy with a reduced pro-inflammatory profile compared with CAR T cells in pre-clinical models. The TAC receptor was purpose-built to co-opt the natural T cell activation machinery and lacks the costimulatory signaling typically incorporated in CAR designs. This thesis investigates strategies to augment TAC T cell function against for multiple myeloma through the evaluation of ancillary pharmacological and protein stimuli that would complement the anti-tumor functions of TAC T cells without modifying the TAC receptor design. In chapter 2, I investigated a strategy combining TAC T cells with the SMAC mimetic LCL161 to provide transient costimulatory effects. While LCL161 boosted TAC T cells survival and proliferation, the drug also enhanced susceptibility of TAC T cells to apoptosis and offered no advantage to the TAC T cells when challenged with myeloma. In chapter 3, I engineered TAC T cells to secrete IL-27 in an attempt to modulate the myeloma microenvironment and support T cell cytolytic function. IL-27 did not enhance the anti-tumor activity of TAC T cells but forced expression of IL-27 led to a reduction in the production of pro-inflammatory cytokines without altering cytotoxicity. In appendix I, I describe the process of optimizing CRISPR/Cas9 editing of primary TAC T cells. This methodology was required for much of the work in chapter 2. Ph.D. Thesis – Arya Afsahi McMaster University – Biochemistry and Biomedical Sciences v In appendix II, I describe an assessment of mRNA-engineering as a method to produce TAC T cells. This approach proved to be therapeutically futile and was not pursued beyond the work described herein. The work presented here highlights methods of combining TAC T cells with a clinically relevant SMAC mimetic, or the cytokine IL-27, and provides insights into the biological mechanisms that are affected by these approaches. / Thesis / Doctor of Philosophy (PhD)
28

Synthesis and studies of carbohydrate mimetics as glycosidase inhibitors and molecular switches

Brazdova, Barbora 01 January 2006 (has links) (PDF)
Part I . We explored the synthesis of a C -glycoside synthesis from L-fucose and malononitrile in the presence of a base catalyst. The reaction was much faster than the previously studied Henry condensation, and went further---to a double cyclization of 2:1 adduct with a novel dioxabicyclic structure. It provides a new route for the synthesis of chiral polysubstituted dihydropyrans and dihydropurans. A series of carbasugars was synthesized and tested for inhibitory activity towards fungal glycosidases from Aspergillus oryzae and Penicillium canescens . In order to reveal the dependence of inhibition on the alkyl group R, several derivatives with variable alkyl chain lengths were prepared and screened. Part II . Cyclohexane-based conformationally controlled ionophores, an emerging new class of molecular switches, provide a new and promising approach to allosteric systems with negative cooperativity. Protonation of trans -2-aminocyclohexanols was observed to cause dramatic conformational changes: due to an intramolecular hydrogen bond, a conformer with equatorial position of ammonio- and hydroxy-groups becomes predominant. This signal is mechanically transmitted by the structure of the molecule, inducing a conformational change in the second site and decreasing its affinity for an appropriate guest. Thus, these structures can serve as powerful conformational pH-triggers. The trans -2-aminocyclohexanol moiety has been used for pH-triggered conformational switching of crown ethers and podands, and their complexes with metal ions. The variation of the NR 2 group allows broad tuning of the conformational equilibrium, and thus tuning of the complexing ability of these allosteric ionophores. Heterotropic allosteric systems with high negative cooperativity may find many applications, such as membrane transport and drug delivery.
29

Combination of calorie restriction mimetics improves health span in short-lived PEPCK bGH transgenic mice

Gautam, Anil 01 December 2023 (has links) (PDF)
Aging is the major risk factor for chronic age-related diseases characterized by loss of homeostasis, organ dysfunction, and inflammation. Calorie restriction (CR) has been shown to slow aging and delay the onset of chronic age-related diseases. Even though CR has many positive health effects, the degree and duration of the restriction needed would reduce the intervention's usefulness and make it challenging to start and maintain in humans. The difficulties brought on by CR have led to the development of CR mimetics that can mimic the effects of CR without reducing food intake (in an ad libitum state). We hypothesize that in PEPCK bovine Growth Hormone (bGH) overexpressing transgenic mice with accelerated metabolic and cognitive aging, the health span and phenotypes of aging can be improved by adding CR mimetics, a combination of lipoic acid, nicotinamide, thiamine, pyridoxine, and piperine to the diet. From 10 to 40 weeks of age, bGH-tg mice and their normal (N) littermates were fed CRM diet ad libitum. Normal littermates and bGH-tg mice fed a standard chow diet served as controls. Evaluation of the effects of CRM included insulin and glucose tolerance tests (ITT and GTT), indirect calorimetry as well as rotarod, working memory, grip strength testing. Body weight and percent fat mass were significantly lower, but percent lean mass was significantly higher in mice on a CRM diet at 40 weeks. At 19 weeks, insulin sensitivity was improved considerably in treated N and bGH-tg males. At 20 weeks of age, all mice on a CRM diet had significantly improved glucose tolerance and lower fasting glucose. At week 32, treated N female mice had significantly higher energy expenditure during the day and night per gram of body weight. In treated N males, this was true only during the day. Male bGH-tg mice on CRM diet had decreased energy expenditure during the night. Insulin sensitivity was significantly improved in treated male N and bGH-tg mice at week 37. Week 38 GTT showed enhanced glucose tolerance and lower fasting glucose in all mice on a CRM diet except Tg females. Week 39-40 Y-maze, rotarod and grip strength testing showed improved motor coordination and grip strength in all mice on CRM diet with no difference in working memory. Also, there was a significant improvement in metabolic and aging phenotype with lowered pro-inflammatory cytokines at the gene and protein levels in various tissues. Our study indicates the employed CRM produce the beneficial health effects in short-lived, insulin resistant bGH Tg mice but the effects are time-, sex-, genotype-, and diet-dependent. Most of the effects of this intervention resemble the effects of CR suggesting that employed compounds may act via similar mechanisms. This work was funded by the SIU-SOM Geriatrics Research Initiative (AB), NIA R01AG068288, and the Hillblom Foundation (PK).
30

Testing glycomimetic compounds for their ability to disrupt capsular polysaccharide production in type 5 Staphylococcus aureus

Pavlidakey, Katherine Irene 02 September 2008 (has links)
No description available.

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