University, Diss., 2002--Regensburg.

Universiẗat, Diss., 2005--Frankfurt (Main).

University, Diss., 2005--Jena.

Univ., Diss., 2006--Frankfurt (Main)

Many cognitive and neurological disorders today, such as Autism Spectrum Disorders (ASD) and various forms of epilepsy such as infantile spasms (IS), manifest as changes in voltage activity recorded in scalp electroencephalograms (EEG). Diagnosis of brain disease often relies on the interpretation of complex EEG features through visual inspection by clinicians. Although clinically useful, such interpretation is subjective and suffers from poor inter-rater reliability, which affects clinical care through increased variability and uncertainty in diagnosis. In addition, such qualitative assessments are often binary, and do not parametrically measure characteristics of disease manifestations. Many cognitive disorders are grouped by similar behaviors, but may arise from distinct biological causes, possibly represented by subtle electrophysiological differences. To address this, quantitative analytical tools - such as functional network connectivity, frequency-domain, and time-domain features - are being developed and applied to clinically obtained EEG data to identify electrophysiological biomarkers. These biomarkers enhance a clinician’s ability to accurately diagnose, categorize, and select treatment for various neurological conditions. In the first study, we use spectral and functional network analysis of clinical EEG data recorded from a population of children to propose a cortical biomarker for autism. We first analyze a training set of age-matched (4–8 years) ASD and neurotypical children to develop hypotheses based on power spectral features and measures of functional network connectivity. From the training set of subjects, we derive the following hypotheses: 1) The ratio of the power of the posterior alpha rhythm (8–14 Hz) peak to the anterior alpha rhythm peak is significantly lower in ASD than control subjects. 2) The functional network density is lower in ASD subjects than control subjects. 3) A select group of edges provide a more sensitive and specific biomarker of ASD. We then test these hypotheses in a validation set of subjects and show that both the first and third hypotheses, but not the second, are validated. The validated features successfully classified the data with significant accuracy. These results provide a validated study for EEG biomarkers of ASD based on changes in brain rhythms and functional network characteristics. We next perform a follow-up study that utilizes the same group of ASD and neurotypical subjects, but focuses on differences between these two groups in the sleep state. Motivated by the results from the previous study, we utilize the previously validated biomarkers, including the alpha ratio and the subset of edges found to be a sensitive biomarker of ASD, and test their effectiveness in the sleep state. To complement these frequency domain features, we also investigate the efficacy of several time domain measures. This investigation did not lead to significant findings, which may have important implications for the differences between sleep and wake states in ASD, or perhaps generally for clinical assessment, as well as for the effect of noise on signal in clinically obtained data. Finally, we design a similar analysis framework to investigate a set of clinical EEG data recorded from a population of children with active infantile spasms (IS) (2-16 months), and age-matched neurotypical children, in both wake and sleep states. The goal of this analysis is to develop a quantitative biomarker from the EEG signal, which ultimately we will apply to predict the clinical outcome of children with IS. In addition to spectral and functional network analysis, we calculate time domain features previously found to correlate with seizures. We compare the two populations by each feature individually, test the effects of age on these features, use all features in a linear discriminant model to categorize IS versus neurotypical EEG, and test the findings using a leave-one-out validation test. We find almost every feature tested shows significant population differences between IS and control groups, and that taken together they serve as an effective classifier, with potential to be informative as to disease severity and long-term outcome. Furthermore, analysis of these features reveals two groups, indicating a possibility that these features reflect two distinct qualitative characteristics of IS and seizures.

Leukocyte telomere length is an emerging marker for pathologically accelerated cellular aging. First discovered to be associated with aging-related disorders, such as type 2 diabetes mellitus and cardiovascular disease, in young individuals, leukocyte telomeric degeneration is also garnering growing attention in psychiatric illnesses. Comorbid metabolic symptoms and physiological dysregulation observed in schizophrenia patients imply a plausible association between pathological telomere biology and psychosis. Available data on the relationship between leukocyte telomere length and schizophrenia is limited largely to small-sample, cross-sectional studies unable to fully account for the large body of potentially confounding factors on telomere length (psychotropic medication, chronic stress and history of trauma, comorbidities, paternal age, substance use, subject-level variables). The most comprehensive meta-analysis to date reveals a significant trend of shortened telomeres in schizophrenia patients as compared to healthy controls. Some findings suggest a linear relationship between telomeric attrition and disease chronicity/severity. However, overall findings are insufficient to gauge the potential of leukocyte telomere length as a predictive, diagnostic biomarker in this patient population. Future longitudinal studies with carefully controlled covariates are required to verify the promising potential of a new marker for schizophrenia onset and a possible new direction for adjunctive antipsychotic treatment.

abstract: Background: Twenty-four hour urinary sucrose and fructose (24uSF) has been developed as a dietary biomarker for total sugars intake. Collection of 24-h urine is associated with high costs and heavy participant burden, while collection of spot urine samples can be easily implemented in research protocols. The aim of this thesis is to investigate the utility of uSF biomarker measured in spot urine. Methods: 15 participants age 22 to 49 years completed a 15-day feeding study in which they consumed their usual diet under controlled conditions, and recorded the time each meal was consumed. Two nonconsecutive 24-hour urines, where each urine void was collected in a separate container, were collected. Four timed voids (morning, afternoon, evening, and next day) were identified based on time of void and meal time. Urine samples were measured for sucrose, fructose and creatinine. Variability of uSF excretion was assessed by coefficient of variation (%CV) and variance ratios. Pearson correlation coefficient and multiple linear regression were used to investigate the association between uSF in each timed void and corresponding 24uSF excretion. Results: The two-day mean uSF was 50.6 mg (SD=29.5) for the 24-h urine, and ranged from 4.5 to 7.5 mg/void for the timed voids. The afternoon void uSF had the lowest within-subject variability (49.1%), and lowest within- to between-subject variance ratio (0.2). The morning and afternoon void uSF had the strongest correlation with 24-h uSF for both mg/void (r=0.80 and r=0.72) and mg/creatinine (r=0.72 and r=0.67), respectively. Finally, the afternoon void uSF along with other covariates had the strongest predictive ability of 24-h uSF excretion (mg/void) (Adjusted R2= 0.69; p=0.002), whereas the morning void had the strongest predictive ability of 24-h uSF excretion (mg/g creatinine) (adjusted R2= 0.58; p=0.008). Conclusions: The afternoon void uSF had the most favorable reproducibility estimates, strong correlation with 24uSF excretion, and explained greatest proportion of the variability in 24uSF. USF in mg/void may be better to use than uSF in mg/g creatinine as a biomarker in spot urine. These findings need to be confirmed in a larger study, and in a study population with a wide range of sugars intake. / Dissertation/Thesis / Masters Thesis Nutrition 2018

Mes travaux de thèse ont permis d’identifier nectine-4 comme un nouveau biomarqueur, facteur de pronostic et cible thérapeutique dans 63% des cancers du sein triple-négatif (TNBC). Les TNBCs (20% des cancers du sein) sont de mauvais pronostics car, en dehors de la chimiothérapie, il n’existe pas de traitement dit « ciblé ». Ces travaux vont permettre à court terme d’adapter la stratégie thérapeutique et d’améliorer la prise en charge des patientes TNBC en fonction de leur profil d’expression de nectine-4. En effet, nous proposons une thérapie ciblée fondée sur la stratégie Antibody Drug Conjugate « ADC » anti-nectine-4 dans les TNBC équivalent au trastuzumab-emtansine dans le cancer du sein HER2+. Nous avons produit, sélectionné et validé cet outil thérapeutique innovant. Nous avons couplé cet anticorps à la monomethyl auristatin-E (MMAE) et testé son efficacité in vitro et in vivo en utilisant des modèles précliniques de souris PDX (Patient Derived Xenograft) greffées en conditions orthotopiques avec des tumeurs primaires TNBC. Nos résultats obtenus sur les tumeurs primitives et métastatiques sont très prometteurs, puisqu’il est possible de réduire voire de faire disparaitre la masse tumorale très rapidement après un seul traitement à la fois au niveau des tumeurs primitives, des métastases positives pour nectine-4. Cet anticorps anti-nectine-4 a fait l’objet d’un brevet international, a été humanisé et est en cours de développement clinique au sein d’une industrie pharmaceutique. Il est actuellement testé pour sa toxicité et son efficacité chez le singe cynomolgus. / Nectin-4 has been identified as a breast and ovarian biomarker at CRCM. Nectin-4 is a celladhesion molecule belonging to the immunoglobulin superfamily and is involved in ectodermaldevelopment in human. Nectin-4 has been recently identified as the epithelial receptor for themeasles virus. Together, this work has been rewarded by Inserm in 2012 (Prix del’Innovation). During my thesis, I have characterized nectin-4 as new prognosis biomarker andtherapeutic target in 63% of triple-negatif breast cancer (TNBC) . TNBCs represent 20% ofbreast cancer and are associated with poor prognosis as there is no exisiting targeted therapy.These results open the possibility for Antibody Drug Conjugate (ADC)-based targetedtreatment of primary and advanced TNBCs similar to trastuzumab-emtansine for HER2-positive breast cancers. We selected and validated a monoclonal antibody against nectin-4ectodomain and developed an ADC conjugated to monomethyl auristatin-E (MMAE). Weassessed the therapeutic efficiency of this ADC in vitro and in vivo in localised and metastaticTNBC Patient derived Xenografts (PDXs). In vivo, this ADC induced rapid, complete anddurable responses on nectin-4-positive xenograft TNBC samples including primary tumours,metastatic lesions, and local relapses. This antibody has been humanized, patented and iscurrently under clinical development by a pharmaceutical company testing toxicity and efficacyin cynomolgus monkeys.

Philosophiae Doctor - PhD / There are over 100 different types of cancer, and each of these cancers are classified by the type of cell that it initially affects. For the purpose of this research we will be focussing on prostate cancer (PC). Prostate cancer is the second most common form of cancer in men around the world and annually approximately 4500 men in South Africa are diagnosed making PC a global epidemic. Prostate cancer is a type of cancer which starts in the prostate it is normally a walnut-sized gland found right below the bladder. PC follows a natural course, starting as a tiny group of cancer cells that can grow into a tumour. In some men if PC is not treated it may spread to surrounding tissue by a process called direct invasion/ spread and could lead to death. Current diagnostic tests for prostate cancer have low specificity and poor sensitivity. Although many PC's are slow growing there is currently no test to distinguish between these and cancers that will become aggressive and life threatening. Therefore the need for a less invasive early detection method with the ability to overcome the lack of specificity and sensitivity of current available diagnostic test is required. Biomarkers have recently been identified as a viable option for early detection of disease for example biological indicators ie. DNA, RNA, proteins and microRNAs (miRNAs). Since first described in the 1990s, circulating miRNAs have provided an active and rapidly evolving area of research that has the potential to transform cancer diagnostics and prognostics. In particular, miRNAs could provide potentially new biomarkers for PC as diagnostic molecules. Circulating miRNAs are highly stable and are both detectable and quantifiable in a range of accessible bio-fluids, having the potential to be useful as diagnostic, prognostic and predictive biomarkers. In this study we aimed to identify miRNAs as potential biomarkers to detect and distinguish between various types of PC in its earliest stage. The major objectives of the study were to identify miRNAs and their gene targets that play a critical role in disease onset and progression to further understand their mechanism of action in PC using several in silico methods, and to validate the potential diagnostic miRNAs using qRT-PCR in several cell lines. The identification of specific miRNAs and their targets was done using an "in-house" designed pipeline. Bioinformatic analyses was done using a number of databases including STRING, DAVID, DIANA and mFold database, and these combined with programming and statistical analyses was used for the identification of potential miRNAs specific to PC. Our study identified 40 miRNAs associated with PC using our "in-house" parameters in comparison to the 20-30 miRNAs known to be involved in PC found in public databases e.g. miRBase. A comparison between our parameters and those used in public databases showed a higher degree of specificity for the identification PC-associated miRNAs. These selected miRNAs were analysed using different bioinformatics tools, and were confirmed to be novel miRNAs associated with PC. The identified miRNAs were experimentally validated using qRT-PCR to generate expression profiles for PC as well as various other cancers. Prostate lines utilised in this study included PNT2C2 (normal) which was compared to BPH1 (Benign) and LNCaP (Metastatic). In the study the expression profiles of eight potential miRNA biomarkers for the detection of PC was determined using qRT-PCR, and to distinguish PC from other cancers. QRT-PCR data showed that miRNA-3 and -5 were up-regulated in the BPH1 and LNCaP when compared to PNT2C2. In addition miRNA-8 was also shown to be up-regulated in LNCaP. Based on these results it was shown that a miRNA profile could be established to distinguish between BPH1 and the LNCaP prostate cell lines. The results suggest that one miRNA as a diagnostic marker may be sufficient to differentiate between different cancer cell lines. Furthermore by creating a unique profile for each cancer cell line by using a combination of miRNAs could be a suitable approach as well. Finally, it was shown that through the use of a single or combination of all eight miRNAs a unique profile for all the cancer cell lines tested in this study can be created. This is an important finding which could have potential diagnostic or prognostic implications in clinical practice.

Arsenic (As) exposure is associated with cancer, lung and cardiovascular disease, yet the mechanisms involved are not clearly understood. Elevated matrix metalloproteinase-9 (MMP-9) levels are also associated with these diseases, as well as with exposure to water As. Our objective was to evaluate the effects of dietary components of inorganic As (iAs) intake on serum MMP-9 concentration at differing levels of tap water As. In a cross-sectional study of 214 adults, dietary iAs intake was estimated from 24-h dietary recall interviews using published iAs residue data; drinking and cooking water As intake from water samples and consumption data. Aggregate iAs intake (food plus water) was associated with elevated serum MMP-9 in mixed model regression, with and without adjustment for covariates. In models stratified by tap water As, aggregate intake was a significant positive predictor of serum MMP-9 in subjects exposed to water As≤10 μg/l. Inorganic As from food alone was associated with serum MMP-9 in subjects exposed to tap water As≤3 μg/l. Exposure to iAs from food and water combined, in areas where tap water As concentration is ≤10 μg/l, may contribute to As-induced changes in a biomarker associated with toxicity.