The use of food supplements containing natural chemopreventive compounds increased in recent years. Some of the most popular chemopreventive compounds are flavonoids. Due to their natural origin, flavonoids are generally accepted as safe compounds. They exert antioxidant, anti-cancer and anti-inflammatory properties. However, flavonoids should be considered as foreign compounds (xenobiotics). Flavonoids interact with many enzymes, among the most important belong cytochromes P450 (CYPs), key enzymes of the first phase of biotransformation of xenobiotics (e.g. drugs, carcinogens). CYPs catalyze reactions leading mainly to detoxification of xenobiotics. However, some CYPs are involved in the activation of carcinogens, particularly CYP1A1 and CYP1A2 activate e.g. heterocyclic amines. Flavonoids might enhance the activation of carcinogens via induction of these CYPs or stimulation of their activities and hence, increase the risk of a cancer development. The thesis is focused on the influence of flavonoids and food carcinogens on the induction and activity of CYP1A1 and CYP1A2 in liver and small intestine of rats. For the purpose of this study, the small intestine was dissected into three parts: proximal (nearest to stomach), middle and distal. Western blotting was used for the evaluation of CYP...

Assim como tecidos normais, tumores possuem uma demanda de nutrientes e oxigênio, suprida através da vasculatura a eles associada que resulta do processo de angiogênese. Fatores pró-angiogênicos são capazes de atrair monócitos, os quais se diferenciam em macrófagos associados a tumores (TAMs). TAMs comumente apresentam fenótipo M2, cujas características são consideradas pró-tumorais, como a promoção da angiogênese e a degradação de matriz extracelular. Estudos indicam que galectina-3 (gal-3), uma proteína pleiotrópica que se liga a ?-galactosídeos, participa do controle da angiogênese e da infiltração de macrófagos M2 na massa tumoral, mas pouco se sabe sobre os mecanismos envolvidos. No presente estudo, utilizamos um modelo de sarcoma induzido por carcinógeno em camundongos selvagens (WT) e knockout para gal-3 (Gal- 3 KO). Comparando os tumores de animais WT e Gal-3 KO, não observamos diferenças no padrão de crescimento tumoral, na área necrótica relativa, na proliferação celular e na quantificação de fibras de colágeno. Demonstramos que, embora ambos os grupos desenvolvam tumores, a angiogênese foi inibida em um microambiente desprovido de gal-3. Entretanto, não houve diferença na produção do fator de crescimento endotelial vascular (VEGF). As imagens obtidas in vivo indicaram que gal- 3 também influencia na formação estrutural de vasos adjacentes ao tumor. Além de mediar aspectos morfológicos relacionados à angiogênese, demonstramos que gal-3 também contribuiu para a funcionalidade vascular, pois houve uma redução na velocidade de fluxo sanguíneo nos vasos intratumorais de animais Gal-3 KO. Nossos dados sugeriram que há menos macrófagos no tumor que não expressa gal-3 e, dentre os TAMs, há mais M2 em comparação ao tumor gal-3-positivo. A análise do tecido onde o tumor se desenvolve, na fase inicial da tumorigênese, indicou que a ausência de gal-3 está relacionada a uma maior densidade de macrófagos M2. Considerando que a presença maior de macrófagos M2 nos sarcomas gal-3-negativos não resultou em maior produção de VEGF, mas sim na inibição da angiogênese, nossos resultados apontam para uma participação significativa de gal-3 na mediação da angiogênese pelos macrófagos / As well as normal tissues, tumors require nutrients and oxygen, which are supplied by the associated vasculature that results from the process of angiogenesis. Pro-angiogenic factors are able to attract monocytes and they differentiate into tumor-associated macrophages (TAMs). TAMs commonly exhibit M2 phenotype, which has characteristics considered pro-tumoral, such as angiogenesis promotion and degradation of extracellular matrix. Studies show that galectin-3 (gal-3), a pleiotropic ?-galactosidebinding protein, participates in angiogenesis control and M2 macrophage infiltration into the tumor mass, but little is known about the mechanisms involved. In this work, we established a model of carcinogen-induced sarcoma in wild-type (WT) and gal-3 knockout (Gal-3 KO) mice. Comparing tumors from WT and Gal-3 KO animals, there were no differences in the pattern of tumor growth, relative necrotic area, cell proliferation and collagenous fibers. We demonstrated that, although both groups develop tumors, angiogenesis was inhibited in a microenvironment devoid of gal-3. However, there was no difference in the production of vascular endothelial growth factor (VEGF). The images obtained in vivo indicated that gal-3 also influenced the structural formation of vessels adjacent to the tumor. In addition to mediating morphological aspects related to angiogenesis, we demonstrated that gal-3 also contributes to vascular functionality, since there was a reduction in blood flow velocity in intratumoral vessels from Gal-3 KO animals. Our data suggested that there are fewer macrophages in tumors without gal-3 and, among TAMs, there are more M2 compared to gal-3-positive tumors. Analysis of the tissue where the tumor develops, in early stages of tumorigenesis, indicated that the lack of gal-3 is related to an increased density of M2 macrophages. Since the greater number of M2 macrophages in gal-3-negative fibrosarcomas did not result in increased VEGF production, but inhibited angiogenesis, our results suggest a significant role of gal-3 in regulation of angiogenesis by macrophages

Wang, Shiyan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 123-139). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

The use of bioimpedance techniques for malignancy identification is considered novel, with challenges existing that need to be overcome. In this thesis, such bioimpedance approaches have been developed for identifying malignancies through a systematic study, ranging from the investigation of the technical challenges affecting an imaging based breast cancer detection system, to the study of electrical properties of tissue and cells. Hence, this work provides proof-of-concept for cancer diagnosis based on the electrical signatures that differentiate malignancies from normal tissue, utilising bioimpedance analysis techniques. Further, this work will contribute to the understanding of correlations between electrical properties and biological functions, which will help to explore bioimpedance techniques for wider medical and bioscience applications. Furthermore, this research will also be conducive to investigations of novel devices for cancer diagnosis in clinic. The Ph. D work was carried out in two threads. In the first thread, technical challenges of using Electrical Impedance Mammography (EIM), an imaging modality developed based on bioimpedance technique for breast cancer diagnosis, were studied on 1) effectively reducing measurement errors from electrode contact interfaces, and 2) validating systems by using novel simulation phantoms. In the second thread, bioimpedance spectroscopy (BIS) of tissues and cells was investigated to 1) reveal their electrical properties, 2) identify malignant changes, and 3) establish correlations of electrical properties with biological function changes. By carrying studies in these two threads, bioimpedance was fully investigated for its applications on cancer detection and diagnosis. This work has made significant contributions to the field of study. It comprises the first systematic study on bioimpedance for cancer identification at the tissue and cellular levels. This work has also been pioneering in linking the electrical properties of malignant tissues and cells to the relevant biological changes brought on by the aforementioned malignancies.

The Electrical Impedance Mammography (EIM) device is an imaging system developed at the University of Sussex for the detection of breast lesions in vivo using quadrature detection of impedance. The work describes a novel technique to integrate Ultrasound-guided Focused Ultrasound Surgery (USgFUS) with the existing EIM system. The benefits that such a system could provide include the possibility of non-invasive detection, diagnosis and treatment of breast cancer all within a single device and involving no radiation. Furthermore the timescales involved would allow the process to be considered an outpatient procedure such that a patient can be diagnosed and treated on the same day using the same device. Various geometries of transducer were investigated for physical compatibility as well as the ability to target the entire specified volume, based on the dimensions of the existing system. Simulations were performed using a custom written code based on Huygen's principle, allowing minimum surface area and power requirements to be determined and feasibility of designs to be evaluated. The use of phase differences in the excitation signals applied to individual elements was also investigated, thus the effect of steering the simulated focus could be observed, an important factor to consider when attempting to incorporate a transducer into a device with restricted dimensions. Resulting simulated pressure fields were used to obtain acoustic intensity fields, which could then be used as inputs in the Pennes Bio-Heat Transfer Equation (BHTE) allowing temperature distributions to be observed. Preliminary studies proved the feasibility of using the suggested transducer design in conjunction with the existing EIM system. Pressure fields and heating patterns were all within acceptable limits, confirming the ability of the device to effectively ablate cancerous tissue. Additionally the capability to steer the resultant focal point was validated, and a thermal dose model was implemented allowing different heating patterns to be quantitatively compared.

The thesis examines the complex relationship between individual experiences of breast cancer and the wider social, political and discursive context in which they are located. It focuses on how Spanish women living with breast cancer define their own health priorities by exploring their experiences and their dissatisfactions, which appear to have been excluded from public and biomedical discourses. The data was collected in a provincial city in Western Spain and focused on the lived experiences of 32 women living and surviving breast cancer. Interviews were mainly conducted in the headquarters of the Spanish Association against Cancer of that region, but also at women's homes and in other public spaces. Based upon a framework of narratives of resistance, grounded in feminist theory, critical medical anthropology and sociology, an ethnographic approach allowed a focus on breast cancer patients and survivors as ‘experts' of their own health, addressing fundamental concerns in the production of knowledge. The thesis discusses the relationship between breast cancer and social inequality. It examines the dramatic ways that structures of power such as class, age, gender, and disability, intersect and “conspire” through a web of social beliefs, practices, norms and expectations to shape, and exacerbate, women's experiences of illness, in particular, of those women who need health care the most. The research also highlights the ways in which the experiential symptoms of breast cancer are portrayed and perceived in public and medical discourses in sexual terms or physiological terms, which ignores the wider social and embodied contexts of women's experiences. By answering the call made by feminist writers such as Wilkinson (2001) and Broom (2000) to listening to the narratives of resistance of these Spanish women, this study therefore offers both a particular cultural account of their collaboration with a range of institutions such as health professionals, charities, the family and the social care system, but also valuable lay experiences which are more generally relevant to wider healthcare practice and policy.

Worldwide, breast cancer accounts for 22% of all cancer incidences in women, causing 458,503 deaths per annum [WHO 2008]. The most common screening method is X-ray mammography, an ionising method, which has many technical and age group limitations and has come under scrutiny for accuracy and safety on many occasions. Electrical Impedence Mammography (EIM) is a novel, non-invasive, non-ionising imaging modality based on bioimpedence. Initial test results show it as very promising; however the image resolution is quite low. Ultrasound imaging is widely used for high-resolution medical imaging and clinical diagnostics. Ultrasound is non-invasive and is effective in imaging soft body tissue, including subcutaneous structures and organs, but fails to distinguish tissue type. Merging the information of the above modalities and integrating them in an automated device offers a safe, non-invasive, fast, higher accuracy, breast cancer detection method for all age groups. To explore the proposed system, the work was divided into cumulative integrative stages: investigation of the technical challenges of a real world breast scanner device for each modality and the combination of both, including engineering, repeatability, safety and ergonomics, to adhere to medical device standards; data acquisition systems design, signal processing and calibration; image geometry correction; 3D image reconstruction; volumetric merger and visualisation; validation with dual modality scans on phantom and in-vivo; DICOM image porting. These modalities were successfully combined in a unified automated breast scanner that can accommodate and scan 95% of women (breast volume up to 1200cc) in a safe and comfortable way. Data acquisition and scan time achieved is five minutes per breast. The image results achieved from this research complement each other by integrating the boundary information of Ultrasound with the impedence data and tissue discrimination of EIM, therefore potentially providing a more complete and accurate cancer diagnostic method. The images were successfully ported into the DICOM radiology imaging standard therefore becoing platform independent. This work concluded with over twenty academic publications and two filed patents on the technology of a breast scanner and on the methodology of its imaging.

Epstein-Barr virus is a gamma herpesvirus that is present in human adult's B-lymphocytes infecting 90% of the global population. EBV causes many types of lymphoma and carcinoma. The virus life cycle can be divided in two stages, latency and lytic cycle. Viral gene BZLF1 codes for the viral transcription and replication factor Zta (also known as BZLF1, ZEBRA, EB1, and Z) which is part of the signalling required to switch from latency to the lytic cycle. Zta is part of the bZIP family of proteins, it forms homodimers and can bind to specific sequences termed Zta Response Elements (ZREs). It binds to the EBV lytic origin of replication as well as to specific targeted promoters in the viral genome and regulates its expression. Recent research found and mapped interactions between the key viral transcription factor Zta and the B-cell genome, this showed interactions of Zta proximal (closer than 2Kb) and distal (farther than 2 Kb) to the transcription start site of several genes. In this work, I asked the questions: Can enhancer properties be found in the sequences where Zta binds to? Is Zta distally regulating expression by looping of DNA? This was approached first by identifying potential sequences that could be conferring enhancing activity, then inserting them into vectors and transfecting them into two different cell lines. In this way, through luciferase reporter assays, any enhancing capabilities of the sequences were tested when placed in a proximal and distal manner to promoters known to be regulated by Zta, as well as mutated promoters not regulated by Zta. This resulted in finding discreet enhancer activity in the sequences analysed, with some being specific to the cell type that was used in the experiment. To answer the second question, chromosome conformation capture (3C) was used to test the possibility of a spatial rearrangement bringing together distal Zta binding regions and promotor regions of selected genes (looping). However, I did not find evidence of looping between Zta binding sites and the neighbouring promoters analysed, in the cell context employed.

Electrical Impedance Tomography (EIT) is a medical imaging technique that reconstructs internal electrical conductivity distribution of a body from impedance data that is measured on the body surface, and Electrical Impedance Mammography (EIM) is the technique that applies EIT in breast cancer detection. The use of EIM for breast cancer identification is highly desirable because it is a non-invasive and low-cost imaging technology. EIM has the potential in detecting early stage cancer, however there are still challenges that hindering EIM to be provided as a routine health care system. There are three major groups of obstacles. One is the hardware design, which includes the selection of electronic components, electrode-skin contacting methods, etc. Second is theoretical problems such as electrode configurations, image reconstruction and regularization methods. Third is the development of analysis methods and generation of a cancerous tissue database. Research reported in this thesis strives to understand these problems and aims to provide possible solutions to build a clinical EIM system. The studies are carried out in four parts. First the functionalities of the Sussex Mk4 EIM system have been studied. Sensitivity of the system was investigated to find out the strength and weakness of the system. Then work has been made on image reconstruction and regularization methods in order to enhance the system's endurance to noise, also to balance the reconstruction conductivity distribution throughout the reconstructed object. Then a novel cancer diagnosis technique was proposed. It was developed based on the electrical property of human breast tissue and the behaviour or systematic noise, to provide repeatable results for each patient. Finally evaluation has been made on previous EIM systems to find out the major problems. Based on sensitivity analysis, an optimal combined electrode configuration has been proposed to improve sensitivity. The system has been developed and produced meaningful clinical images. The work makes significant contributions to society. This novel cancer diagnosis method has high accuracy for cancer identification. The combined electrode configuration has also provided flexibilities in the designing of current driving and voltage receiving patterns, thus sensitivity of the EIM system can be greatly improved.

Small-molecule DNA interactive compounds are critical as both carcinogens and therapeutic agents. In this research, a synthetic precursor to a known carcinogen, (±)-N’-nitrosonicotine-5’-acetate was synthesized, and its interactions with DNA were evaluated by polyacrylamide gel electrophoresis and electrospray-ionization mass spectrometry. A library of skipped benzimidazolium aza-enediynes which selectively target unmethylated cytosines in presence of unmethylated cytosines were synthesized, and their biological properties were evaluated in a nicking assay and cytotoxicity study. Finally, a series of structural analogs to a antineoplastic agent, UK-1, were synthesized via a biaryl coupling at C2 on the benzoxazole. / text