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In the western world cancer is the second most important cause of death, after heart disease, accounting for 20-25% of all mortalities, and is today probably one of the most feared diseases. Approximately one third of all cancer patients will develop skeletal metastases (secondary bone cancer). Early diagnosis and effective monitoring during treatment is therefore essential in terms of making any impact on survival rates and developing new cancer therapies. Unfortunately, the current methods for diagnosing and measuring bone metastases, such as bone scans and urinary hydroxyproline determinations, lack sensitivity and specificity. The urinary pyridinium crosslinks, pyridinoline (PYD) and deoxypyridinoline (DPYD), have recently been identified as sensitive and specific markers of bone breakdown. However the analysis of the pyridinium crosslinks using high performance liquid chromatography (HPLC) has proved far from ideal for routine clinical assessment. The results from studies to critically evaluate this method are presented and particular problems encountered when the crosslinks are extracted from the urine samples are discussed. The tedious, time consuming and cumbersome sample preparation procedure are also shown to adversely effect the robustness and reproducibility of the method. The recent introduction of an immunoassay method potentially overcomes many of the inherent problems with the HPLC analysis. This enzyme linked immunoasorbant assay (ELISA) is evaluated and found to compare favourably with the HPLC method, offering several distinct advantages. The method is quick, simple, robust, demonstrates good accuracy and precision, is less prone to interferences and can be easily introduced into clinical laboratories on a routine basis. In addition it also minimises sample preparation time. However, there is still a requirement for alternative and better biochemical markers to measure bone breakdown. It is well known that bone is an active, living tissue and that bone metabolism and remodelling are tightly coupled processes, where the rate of bone formation equals the rate of bone resorption in healthy bone. When an imbalance occurs, this leads to unhealthy bone and ultimately a clinical disease of the skeleton. Some trace metals, e.g lead, accumulate in the bone and since the development of bone metastases results in extensive bone breakdown, the subsequent release of these metals into the blood and urine may potentially serve as markers. In this work inductively coupled plasma-mass spectrometry (ICP-MS) has been used and methods developed to determine such metals in clinical matrices. The development of a simple dilution method is described for use in preliminary trials to measure the blood lead levels and other trace metal profiles, in patients with bone metastases. The blood lead results attained agree closely with a certified reference material, and the method is shown to remain under analytical control. The trial results are presented and discussed with reference to further and more detailed investigations. The selection criteria for other suitable elements such as AI, Ba, Cd, Ce, Pb, Sr, and Zr in blood and urine, along with an assessment of the analytical and clinical praticalities of the methodology which must be considered for subsequent full clinical trials is also discussed following a critical evaluation. Finally the results obtained in a extended clinical trial are presented. The crosslink levels (serving as the reference marker), measured by ELISA, were compared with the trace metal levels (Cd, Pb and Sr) in blood and urine samples, measured by ICP-MS, in order to assess their diagnostic potential and effectiveness in monitoring treatment. The blood lead levels were found to offer the greatest potential, correlating well with the DPYD values in the majority of cases. The blood strontium levels also showed some promise. However the blood cadmium and the urinary trace metal levels proved less suitable. The results attained in this feasibility study support a more detailed clinical investigation, on a much larger scale, and over a longer period of time. The need to incorporate a full statistical evaluation of all factors that can influence the final results is highlighted.

No description available.

Gene expression profiles have identified five major molecular breast cancer subtypes (Luminal A, Luminal B, Basal-like, HER2+/estrogen receptor− , and Normal Breast-like) that show significant differences in survival. The cost and complexity of gene expression technology has impeded its clinical implementation. By comparison, immunohistochemistry is an economical technique applicable to the standard formalin-fixed, paraffin-embedded material commonly used in hospital labs, and has the advantage of simultaneously interpretation with histomorphology. In this thesis, I hypothesize that a surrogate panel of immunohistochemical biomarkers can be developed to discriminate the breast cancer biological subtypes. The main study cohort consists of over 4000 primary invasive breast tumors, assembled into tissue microarrays. These patients were referred to the British Columbia Cancer Agency between 1986-1992 and have staging, pathology, treatment and follow-up information. In summary, our results demonstrate that (1) the rabbit monoclonal antibody, SP1, is an improved standard for immunohistochemiscal estrogen receptor assessment in breast cancer; (2) the transcription factor, GATA-3, is almost exclusively expressed among estrogen receptor positive tumors but does not seem to predict for tamoxifen response among estrogen receptor positive patients; (3) the proliferation marker, Ki-67, together with HER2 can segregate Luminal A from Luminal B subtypes, which carry distinct risks for breast cancer relapse and death; and (4) the inclusion of the basal markers EGFR and ck5/6 to “triple negative” breast cancers provides a more specific definition of basal-like breast cancer that better predicts patient survival. These results consistently demonstrate that an immunopanel of six biomarkers (estrogen receptor, progesterone receptor, HER2, Ki-67, epidermal growth factor receptor and cytokeratin 5/6) can be readily applied to standard pathology specimens to subtype breast cancer samples based on their underlying molecular biology. These findings have been considered sufficient to justify application of this panel onto NCIC (MA5, MA12) and CALGB (9341 and 9741) clinical trials specimens. This followup work which is underway and will determine if the six marker immunopanel can guide decisions about which patients need aggressive systemic drug treatment, and thereby ensure patients get the most effective, individualized adjuvant systemic therapy for their breast tumor.

Conservation biologists are interested in maintaining genetic variation in small populations, with a view to maintaining fitness and the ability of the species to adapt to changing environmental conditions. The most important type of genetic variation is therefore that which affects fitness and reproduction, and is therefore subject to natural selection. Such fitness traits are often quantitative, i.e. are the result of a suite of loci, and are continuously variable. Microsatellite markers are a popular method of determining the level of variation present in a species??? genome. The assumption is made that microsatellites, which are neutral markers, behave in the same manner as quantitative traits. If this assumption were proved incorrect, then the use of neutral markers in conservation monitoring would have to be re-evaluated. In this study, experiments have been conducted using Drosophila melanogaster to test the assumption that variation in quantitative traits under stabilising selection declines at the same rate as heterozygosity in microsatellite markers, during a population bottleneck. Experimental population bottlenecks were of two effective population sizes (Ne), Ne=2 for one generation and Ne=60 for 35 generations. Based on the effective population size, we expected both types of bottlenecks to lose 25% of neutral genetic variation. Ten replicates of each bottleneck were maintained, along with four large control populations with Ne=320. In each population, heterozygosity (He) for eight microsatellite loci was compared with the heritability and additive genetic variance of two quantitative traits subject to balancing selection: fecundity and sternopleural bristle number. Microsatellite heterozygosity decreased in accordance with neutral predictions, whereas additive genetic variation in quantitative traits altered more than expected in both large and in bottlenecked populations relative to the initial sampling values, indicating that variation in quantitative traits was not being lost at the same rate as predicted by neutral theory. For most traits, the changes in additive genetic variance were congruent in all populations, large or bottlenecked. This congruence suggests that a common process was affecting all populations, such as adaptation. A mite infestation in early generations is a possible source of selective pressure. When bottlenecked populations were compared to the contemporaneous large populations (Ne = 320), the additive genetic variance of most traits was seen to have been lost in accordance with predictions from the loss of microsatellite heterozygosity. Loss of variation in microsatellites can thus be used to predict the loss of variation in quantitative traits due to bottlenecks, but not to predict the potentially much larger changes due to other processes such as adaptation. The effects of concurrent environmental stress and reduced population size were also evaluated. Endangered populations are often subject to environmental stress in addition to reduced population size, but the effect of stress on the additive genetic variance of fitness traits in organisms undergoing population bottlenecks is unknown. If the presence of stress alters the level of additive genetic variance in fitness traits, the viability of such populations could be substantially affected. The loss of microsatellite heterozygosity was not affected by the presence of a stress agent during a bottleneck. I found some significant effects of stress on the additive genetic variance of sternopleural bristles and fecundity; there was also a significant interaction between stress and the response to directional selection in sternopleural bristles. There was also an increase in the coefficient of variation of VA for sternopleural bristles. Stress may therefore affect the manner in which populations respond to selective pressures.

Proefschr. Rijksuniversiteit Groningen. / Met lit. opg.-Met bibl.-Met samenvatting in het Nederlands.

Dissertation (PhD)--University of Stellenbosch, 2007. / Bibliography. Also available on the Internet.

Proefschrift Universiteit van Amsterdam. / Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

Diss. (sammanfattning) Linköping : Univ. / Härtill 6 uppsatser.