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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.
91

The contradictory role of febuxostat in ABCG2 expression and potentiating hypericin‐mediated photodynamic therapy in colorectal cancers

King, A., Maisey, T., Harris, E.L., Poulter, J.A., Jayne, D.G., Khot, Ibrahim 16 April 2025 (has links)
Yes / Photodynamic Therapy (PDT) is an emerging method to treat colorectal cancers (CRC). Hypericin (HYP) is an effective mediator of PDT and the ABCG2 inhibitor, Febuxostat (FBX) could augment PDT. HT29 and HEK293 cells showed light dependant cytotoxic response to PDT in both 2D and 3D cell models. FBX co-treatment was not found to improve PDT cytotoxicity. Next, ABCG2 protein expression was observed in HT29 but not in HEK293 cells. However, ABCG2 gene expression analysis did not support protein expression results as ABCG2 gene expression results were found to be higher in HEK293 cells. Although HYP treatment was found to significantly reduce ABCG2 gene expression levels in both cell lines, FBX treatment partially restored ABCG2 gene expression. Our findings indicate that FBX co-treatment may not be suitable for augmenting HYP-mediated PDT in CRC but could potentially be useful for other applications. / Royal Society International Exchanges Award (IEC\R3\203014) - UKRI EPSRC Research Programme Grant (753910/B19R13527) - Bowel Cancer UK/RCS Eng Colorectal Research Chair Award (18SC0001) / The full-text of this article will be released for public view at the end of the publisher embargo on 16 Apr 2025.
92

β‐Ketoiminato Iridium(III) Organometallic Complexes: Selective Cytotoxicity towards Colorectal Cancer Cells HCT116 p53‐/‐

Lord, Rianne M., Zegke, Markus, Henderson, I.R., Pask, C.M., Shepherd, H.J., McGowan, P.C. 25 October 2018 (has links)
Yes / This report presents a new library of organometallic iridium(III) compounds of the type [Cp*IrCl(L)] (Cp*=pentamethylcyclopentadienyl and L=a functionalized β‐ketoiminato ligand) showing moderate to high cytotoxicity against a range of cancer cell lines. All compounds show increased activity towards colorectal cancer, with preferential activity observed against the immortalized p53‐null colorectal cell line, HCT116 p53‐/‐, with sensitivity factors (SF) up to 26.7. Additionally, the compounds have excellent selectivity for cancerous cells when tested against normal cell types, with selectivity ratios (SR) up to 35.6, contrary to that of cisplatin, which is neither selective nor specific for cancerous cells (SF=0.43 and SR=0.7–2.3). This work provides a preliminary understanding of the cytotoxicity of iridium compounds in the absence of p53 and has potential applications in treatment of cancers for which the p53 gene is absent or mutant.
93

Ultrasound-triggered therapeutic microbubbles enhance the efficacy of cytotoxic drugs by increasing circulation and tumour drug accumulation and limiting bioavailability and toxicity in normal tissues

Ingram, N., McVeigh, L.E., Abou-Saleh, R.H., Maynard, J., Peyman, S.A., McLaughlan, J.R., Fairclough, M., Marston, G., Valleley, E.M.A., Jimenez-Macias, J.L., Charalambous, A., Townley, W., Haddrick, M., Wierzbicki, A., Wright, A., Volpato, M., Simpson, P.B., Treanor, D.E., Thomson, N.H., Loadman, Paul, Bushby, R.J., Johnson, B.R.G., Jones, P.F., Evans, T., Freear, S., Markham, A.F., Evans, S.D., Coletta, P.L. 08 1900 (has links)
Yes / Most cancer patients receive chemotherapy at some stage of their treatment which makes improving the efficacy of cytotoxic drugs an ongoing and important goal. Despite large numbers of potent anti-cancer agents being developed, a major obstacle to clinical translation remains the inability to deliver therapeutic doses to a tumor without causing intolerable side effects. To address this problem, there has been intense interest in nanoformulations and targeted delivery to improve cancer outcomes. The aim of this work was to demonstrate how vascular endothelial growth factor receptor 2 (VEGFR2)-targeted, ultrasound-triggered delivery with therapeutic microbubbles (thMBs) could improve the therapeutic range of cytotoxic drugs. Methods: Using a microfluidic microbubble production platform, we generated thMBs comprising VEGFR2-targeted microbubbles with attached liposomal payloads for localised ultrasound-triggered delivery of irinotecan and SN38 in mouse models of colorectal cancer. Intravenous injection into tumor-bearing mice was used to examine targeting efficiency and tumor pharmacodynamics. High-frequency ultrasound and bioluminescent imaging were used to visualise microbubbles in real-time. Tandem mass spectrometry (LC-MS/MS) was used to quantitate intratumoral drug delivery and tissue biodistribution. Finally, 89Zr PET radiotracing was used to compare biodistribution and tumor accumulation of ultrasound-triggered SN38 thMBs with VEGFR2 targeted SN38 liposomes alone. Results: ThMBs specifically bound VEGFR2 in vitro and significantly improved tumor responses to low dose irinotecan and SN38 in human colorectal cancer xenografts. An ultrasound trigger was essential to achieve the selective effects of thMBs as without it, thMBs failed to extend intratumoral drug delivery or demonstrate enhanced tumor responses. Sensitive LC-MS/MS quantification of drugs and their metabolites demonstrated that thMBs extended drug exposure in tumors but limited exposure in healthy tissues, not exposed to ultrasound, by persistent encapsulation of drug prior to elimination. 89Zr PET radiotracing showed that the percentage injected dose in tumors achieved with thMBs was twice that of VEGFR2-targeted SN38 liposomes alone. Conclusions: thMBs provide a generic platform for the targeted, ultrasound-triggered delivery of cytotoxic drugs by enhancing tumor responses to low dose drug delivery via combined effects on circulation, tumor drug accumulation and exposure and altered metabolism in normal tissues. / EPSRC funding (EP/I000623/1, EP/K023845/1 and EP/P023266/1) and the MRC for a Confidence in Concept award and MR/L01629X. L.E. McVeigh was funded by an EPSRC PhD Studentship (EP/L504993/1).
94

The effect of aspirin and eicosapentaenoic acid on urinary biomarkers of prostaglandin E2 synthesis and platelet activation in participants of the seAFOod polyp prevention trial

Sun, G., Fuller, H., Fenton, H., Race, Amanda D., Downing, A., Williams, E.A., Rees, C.J., Brown, L.C., Loadman, Paul, Hull, M.A. 02 November 2023 (has links)
Yes / Urinary prostaglandin (PG) E metabolite (PGE-M) and 11-dehydro (d)-thromboxane (TX) B2 are biomarkers of cyclooxygenase-dependent prostanoid synthesis. We investigated (1) the effect of aspirin 300 mg daily and eicosapentaenoic acid (EPA) 2000 mg daily, alone and in combination, on urinary biomarker levels and, (2) whether urinary biomarker levels predicted colorectal polyp risk, during participation in the seAFOod polyp prevention trial. Urinary PGE-M and 11-d-TXB2 were measured by liquid chromatography-tandem mass spectrometry. The relationship between urinary biomarker levels and colorectal polyp outcomes was investigated using negative binomial (polyp number) and logistic (% with one or more polyps) regression models. Despite wide temporal variability in PGE-M and 11-d-TXB2 levels within individuals, both aspirin and, to a lesser extent, EPA decreased levels of both biomarkers (74% [P ≤ .001] and 8% [P ≤ .05] reduction in median 11-d-TXB2 values, respectively). In the placebo group, a high (quartile [Q] 2-4) baseline 11-d-TXB2 level predicted increased polyp number (incidence rate ratio [IRR] [95% CI] 2.26 [1.11,4.58]) and risk (odds ratio [95% CI] 3.56 [1.09,11.63]). A low (Q1) on-treatment 11-d-TXB2 level predicted reduced colorectal polyp number compared to placebo (IRR 0.34 [0.12,0.93] for combination aspirin and EPA treatment) compared to high on-treatment 11-d-TXB2 values (0.61 [0.34,1.11]). Aspirin and EPA both inhibit PGE-M and 11-d-TXB2 synthesis in keeping with shared in vivo cyclooxygenase inhibition. Colorectal polyp risk and treatment response prediction by 11-d-TXB2 is consistent with a role for platelet activation during early colorectal carcinogenesis. The use of urinary 11-d-TXB2 measurement for a precision approach to colorectal cancer risk prediction and chemoprevention requires prospective evaluation. / Efficacy and Mechanism Evaluation Programme. Grant Number: NIHR128210. Cancer Research UK. Grant Number: C23434/A24939
95

Improving Colorectal Cancer Screening in Primary Care

Navarrete-Pak, Jenerie Reniedo 01 January 2016 (has links)
Despite indications that colorectal cancer (CRC) screening strategies can decrease mortality and morbidity, screening rates among veterans remains to be low. In the Veterans Affairs (VA), the performance measure for CRC screening is lower than the national standard. This quality improvement (QI) project evaluated the effect of a team-based approach, effective electronic information structures, and the provision of education to nurses and patients in increasing CRC screening rate in primary care from 77% to 85%. CRC screening data were retrospectively collected prior to the start of the project and then compared to screening data 3 months after project implementation. The t test showed a statistically significant increase (p = .009) in CRC screening post intervention. Descriptive analysis was performed to evaluate the knowledge and proficiency of nurses with regard to CRC screening by using pre- and posttest questionnaires. The findings showed that emphasizing the importance of CRC screening among team members as well as appropriately dividing the work was effective in contributing to an increase in CRC screening in primary care. This project contributes to positive social change by increasing the nurses' confidence and proficiency in promoting health and disease prevention among the veterans; decreasing patient suffering; and improving collaboration between providers, nurses, and other departments in the VA primary care.
96

Characterizing the prevalence of chromosomal instability in interval colorectal cancer

Cisyk, Amy L. 10 January 2014 (has links)
Over 80% of colorectal cancers (CRCs) are sporadic/randomly arising tumors. Interval CRCs represent a subset of sporadic tumors that develop within 6-36 months after a negative colonoscopy. Interval CRCs are suggested to exhibit altered biological properties that contribute to rapid growth and proliferation. We hypothesize that chromosomal instability (CIN), or aberrant chromosome numbers, contributes to the etiology of Interval CRCs. We have assembled a Manitoban cohort of Interval and sporadic (control) CRC tumor samples, and established a fluorescence in situ hybridization approach to characterize CIN by enumerating specific chromosomes. The results of this study indicate that 75% of Interval CRCs exhibit a CIN phenotype, making CIN the most prevalent contributor to genomic instability in Interval CRCs. Only once we grasp a better understanding of the tumorigenic pathways through which Interval CRCs develop, can we tailor screening strategies and treatment options to specifically identify and combat this subset of sporadic CRC.
97

Etude des mécanismes de résistance à l'oxaliplatine dans le cancer colorectal : rôle des voies NOX1/Calpaïnes / Study of oxaliplatin resistance mechanisms in colorectal cancer : involvement of NOX1/calpains pathway

Chocry, Mathieu 22 December 2017 (has links)
Le cancer colorectal est un cancer majeur en termes de fréquence et de mortalité. Il s’agit de la deuxième cause de décès par cancer, avec 17 500 décès en France en 2011. Le traitement des stades avancés repose sur différentes molécules anti-cancéreuses telles que l’oxaliplatine. Cependant le développement de résistances entraine des échecs thérapeutiques expliquant le faible taux de survie observé. Il est donc crucial d’identifier les mécanismes de résistance et ses acteurs et de découvrir de nouvelles pistes de traitements.Dans un premier temps, nous nous sommes donc intéressés aux rôles joués par les calpaïnes et NOX1 dans le développement de la résistance à l’oxaliplatine en étudiant des cellules tumorales colorectales résistantes à cette drogue. Ce qui nous a permis d'identifier une voie de signalisation impliquée dans la résistance à cette chimiothérapie.Dans un second temps nous nous sommes intéressés à étudier la réversion de cette résistance à l’oxaliplatine. En criblant différentes chimiothérapies ce qui a permis de mettre en évidence une inversion du statut résistant/sensible dans nos cellules sélectionnées.La première partie de nos données met en évidence de nouvelles régulations de Nox1 qui diffèrent en fonction de la sensibilité des cellules à l’oxaliplatine. Nos résultats montrent aussi que p38 MAPK pourrait être une cible thérapeutique de choix. Dans la deuxième partie nous avons identifié un nouveau traitement permettant l'induction de l'apoptose dans nos cellules résistantes. Ainsi la gemcitabine pourrait être une solution pour traiter les patients ne répondant pas ou plus aux protocoles basés sur l’oxaliplatine / Colorectal cancer is a major cancer in terms of frequency and mortality. This is the second leading cause of cancer death, with 17,500 deaths in France in 2011. The treatment of advanced stages is based on different chemotherapeuties including oxaliplatin. However, the development of resistance leads to therapeutic failures explaining the low survival rate. It is therefore crucial to identify the mechanisms of resistance and the actors involved and to discover new therapeutic approaches. We first investigated the role played by calpains and NOX1 in the development of resistance to oxaliplatin, studying oxaliplatin-resistant colorectal tumor cells. This allowed us to identify a signaling pathway involved in resistance to this chemotherapy.Secondly, we have studied the reversion of this resistance to oxaliplatin. A screening of different chemotherapies revealed a reversal of the resistant / sensitive status in our selected cells In the first part, our data highlight novel Nox1 regulations which differ according to the sensitivity of the cells to oxaliplatin. Our results also show that p38 MAPK could be a therapeutic target for treating colorectal cancers resistant to oxaliplatin. In the second part, we have identified a new treatment to induce apoptosis in our resistant cells. Indeed, gemcitabine may be a solution to treat patients who do not respond to oxaliplatin-based protocols.
98

Factors Affecting Colorectal Cancer Screening Among African-Born Immigrants in the United States

Chibundu, Chidoziri 01 January 2018 (has links)
Despite the evidence that colorectal cancer screening is effective in reducing the incidence of and mortality from colorectal cancer, racial and ethnic disparities in colorectal cancer screening persist in the United States. African-born immigrants in the United States have lower colorectal cancer screening rates than native-born Americans. The purpose of this quantitative, retrospective, cross-sectional study was to examine how family income, health insurance status, language of interview, length of stay in the United States, perceived health status, level of education, and having a usual place for medical care affect colorectal cancer screening among African-born immigrants in the United States. The immigrant health services utilization model provided the framework for the study. Secondary data collected in 2010, 2013, and 2015 through the National Health Interview Survey from 349 African-born immigrants age 40 years and above were analyzed using logistic regression and a chi-square test of independence. A stratified multistage sampling procedure was used to select the sample for the study. Results showed a significant association between colorectal cancer screening and health insurance status, length of stay in the United States, perceived health status, and having a usual place for medical care. However, no association was found between colorectal cancer screening and family income, education level, and interview language. Findings may be used to impact positive social change and guide policy decisions on colorectal cancer preventive interventions targeting African-born immigrants living in the United States.
99

Molecular studies of radiotherapy and chemotherapy in colorectal cancer

Evert, Jasmine January 2015 (has links)
<p>Funding Agency:</p><p>Health Research Council in the South-East of Sweden</p>
100

Evaluating the Role of VDR Polymorphisms and Beta-catenin Signaling in Colorectal Neoplasia

Egan, Jan Bailey January 2009 (has links)
Colorectal cancer is estimated to cause approximately 50,000 deaths each year in the United States. Epidemiological studies have demonstrated an inverse association between sunlight exposure, which stimulates the formation of vitamin D in the skin, and colorectal carcinoma. Laboratory studies report that metabolites of vitamin D, acting through the vitamin D receptor (VDR), regulate cellular proliferation, differentiation and apoptosis. In addition, VDR contains a polymorphic variant, FokI, which results in two different isoforms of VDR. We have demonstrated a differential suppression of β-catenin transcriptional activity by these isoforms in the presence of 1,25(OH)₂D₃ (1,25D). Epidemiological evaluation of metachronous colorectal adenoma formation indicates that VDR includes several single nucleotide polymorphisms (SNPs) which influence the odds of developing colorectal adenoma. In addition, we have found full length Adenomatous Polyposis Coli (APC), a frequently mutated tumor suppressor gene in colorectal cancer, augments both the interaction of VDR and β-catenin as well as the suppression of β-catenin transcriptional activity in the presence of 1,25D. We have also demonstrated in epidemiological studies that the presence of a T-A haplotype in APC codons 486 and 1822, respectively, reduces the odds of any metachronous adenoma by 27% [odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.59 – 0.91]. Taken together, these data support not only a protective role for vitamin D acting through the VDR, but also for an important role of heritable polymorphic variation in VDR and APC in carcinogenesis.

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