Cancer is a disease that involves genomic instability, to which c-Myc contributes during its initiation and progression. Over 70% of all human cancers show deregulated levels of c-Myc protein. The term genomic instability refers to genetic and/or epigenetic changes that alter the normal organization and function of genes and chromosomes. Genomic instability is a hallmark of cancer and often is associated with cancer. Deregulated c-Myc expression generates genomic instability by initiating intra- and extrachromosomally locus-specific gene amplification, gene rearrangements and karyotypic instability that includes translocations, fusions, insertions and deletions. Out of the several outlined pathways by which deregulated levels of c-Myc can lead to genomic instability, the work described in this thesis focuses on three with direct relevance to tumorigenesis; gene amplification (increase in gene copy number), remodeling of the chromosomal and telomeric structures in the interphase nucleus and comparing the effect of Myc to that of Epstein Bar virus (EBV) infection in remodeling the nuclear structure that may lead to genomic instability.

A hearing impairment is one of the three leading causes of disability worldwide. It is estimated that 600 million people around the world have a hearing impairment, which affects their communication abilities, causes them to feel isolated and depressed, and impacts their economic situation. Because a decrease in the ability to hear is associated with getting older and life expectancy is increasing, the number of hearing impaired individuals is expected to increase. Much of the current research on adults with a hearing impairment focusses on a disabling hearing impairment, which is a loss of at least 40 dB HL or worse in the better ear. The research on a mild hearing impairment is predominantly focussed on children, specifically on educational effects. The aims of this study were to identify demographic, audiometric and quality of life differences between adults with a mild hearing impairment who adopt hearing aids and those who choose not to adopt hearing aids, and to measure clinical outcomes for adults with a mild hearing impairment who adopt hearing aids. Two groups of clients with a mild hearing impairment were compared. One group consisted of hearing aid adopters whilst the other group consisted of non-adopters. There was no significant difference between the groups in terms of demographic variables, such as age, gender or working status, or objective audiometric variables. We found a statistically significant difference between the groups in terms of subjective audiometric variables. Hearing aid adopters rated their hearing impairment worse than the non-adopters and were more inclined to change their current situation than the non-adopters. In addition, the adopters showed significant clinical improvement after wearing their hearing aids for an extended period of time.

Cancer is a disease that involves genomic instability, to which c-Myc contributes during its initiation and progression. Over 70% of all human cancers show deregulated levels of c-Myc protein. The term genomic instability refers to genetic and/or epigenetic changes that alter the normal organization and function of genes and chromosomes. Genomic instability is a hallmark of cancer and often is associated with cancer. Deregulated c-Myc expression generates genomic instability by initiating intra- and extrachromosomally locus-specific gene amplification, gene rearrangements and karyotypic instability that includes translocations, fusions, insertions and deletions. Out of the several outlined pathways by which deregulated levels of c-Myc can lead to genomic instability, the work described in this thesis focuses on three with direct relevance to tumorigenesis; gene amplification (increase in gene copy number), remodeling of the chromosomal and telomeric structures in the interphase nucleus and comparing the effect of Myc to that of Epstein Bar virus (EBV) infection in remodeling the nuclear structure that may lead to genomic instability.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 135-143). Also available via the Internet.

Thesis (Ph. D.)--School of Biological Sciences. University of Missouri--Kansas City, 2008. / "A dissertation in molecular biology and biochemistry and cell biology and biophysics." Advisor: Leonard L. Dobens. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Sept. 12, 2008. Includes bibliographical references (leaves 120-147). Online version of the print edition.

Tumor initiation and progression is dependent on the acquisition and accumulation of multiple driver mutations that acti­vate and fuel oncogenic pathways and deactivate tumor suppressor networks. This complex continuum of non-stochastic genetic changes in accompaniment with error-prone mitoses largely explains why tumors are a mosaic of different cells. Contrary to the long-held notion that tumors are dominated by genetically-identical cells, tumors often contain many different subsets of cells that are remarkably diverse and distinct. The extent of this intratumor heterogeneity has bewildered cancer biologists’ and clinicians alike, as this partly illuminates why most cancer treatments fail. Unsurprisingly, there is no “wonder” drug yet available which can target all the different sub-populations including rare clones, and conquer the war on cancer. Breast tumors harbor ginormous extent of intratumoral heterogeneity, both within primary and metastatic lesions. This revelation essentially calls into question mega clinical endeavors such as the Human Genome Project that have sequenced a single biopsy from a large tumor mass thus precluding realization of the fact that a single tumor mass comprises of cells that present a variety of flavors in genotypic compositions. It is also becoming recognized that intratumor clonal heterogeneity underlies therapeutic resistance. Thus to comprehend the clinical behavior and therapeutic management of tumors, it is imperative to recognize and understand how intratumor heterogeneity arises. To this end, my research proposes to study two main features/cellular traits of tumors that can be quantitatively evaluated as “surrogates” to represent tumor heterogeneity at various stages of the disease: (a) centrosome amplification and clustering, and (b) mitotic frequency. This study aims at interrogating how a collaborative interplay of these “vehicles” support the tumor’s evolutionary agenda, and how we can glean prognostic and predictive information from an accurate determination of these cellular traits.

No description available.

The advance of biological research promotes the emerging of new methods and solutions to answer the biological questions. This thesis describes several new molecular tools and their applications for the detection of genomic and proteomic information with extremely high sensitivity and specificity or simplify such detection procedures without compromising the performance. In paper I, we described a general method namely super RCA, for highly specific counting of single DNA molecules. Individual products of a range of molecular detection reactions are magnified to Giga-Dalton levels that are easily detected for counting one by one, using methods such as low-magnification microscopy, flow cytometry, or using a mobile phone camera. The sRCA-flow cytometry readout presents extremely high counting precision and the assay’s coefficient of variation can be as low as 0.5%. sRCA-flow cytometry readout can be applied to detect the tumor mutations down to 1/100,000 in the circulating tumor cell-free DNA. In paper II, we applied the super RCA method into the in situ sequencing protocol to enhance the amplified mRNA detection tags for better signal-to-noise ratios. The sRCA products co-localize with primary RCA products generated from the gene specific padlock probes and remain as a single individual object in during the sequencing step. The enhanced sRCA products is 100% brighter than regular RCA products and the detection efficiency at least doubled with preserved specificity using sRCA compared to standard RCA. In paper III, we described a highly specific and efficient molecular switch mechanism namely RCA reporter. The switch will initiate the rolling circle amplification only in the presence of correct target sequences. The RCA reporter mechanism can be applied to recognize single stranded DNA sequences, mRNA sequences and sequences embedded in the RCA products. In paper IV, we established the solid phase Proximity Ligation Assay against the SOX10 protein using poly clonal antibodies. Using this assay, we found elevated SOX10 in serum at high frequency among vitiligo and melanoma patients. While the healthy donors below the threshold.

Les radicaux peroxydes RO2 (avec R = H ou CxHy) jouent un rôle important dans les cycles de photo-oxydation ayant lieu dans la troposphère. Ils sont produits principalement par l’oxydation des hydrocarbones et du monoxyde de carbone par les radicaux OH suivi de la réaction avec O2. Ils peuvent réagir avec NO pour former du NO2 qui est une source importante d’ozone troposphérique. Pour comprendre les mécanismes de génération de l’ozone troposphérique, des mesures précises et reproductibles des concentrations des radicaux peroxydes sont essentielles. A cela, des études de cinétiques, comme la mesure du temps de vie des radicaux peroxydes, sont nécessaires. Des études récentes ont montré des différences importantes entre les concentrations de radicaux peroxydes mesurées en air ambiant et celles calculées grâce aux modèles de chimie atmosphériques. Ceci peut être dû à des chemins réactionnels manquants et à l’incertitude sur les constantes de vitesses. Deux nouvelles techniques ont été développées afin d’examiner ces différences. La première technique permet la mesure sélective des radicaux HO2 et RO2 par la technique PERCA. Les radicaux HO2 sont ôtés sélectivement en utilisant un « glass denuder ». La seconde technique a pour but la mesure de la vitesse totale de disparition des radicaux HO2 dans l’atmosphère en utilisant la combinaison de la photolyse laser avec la FIL pour la détection de HO2. Les radicaux HO2 générés par photolyse laser réagissent avec les espèces réactives présentes dans l’air ambiant comme les NOx. La vitesse de disparition de HO2 est mesurée en utilisant la FIL à 308 nm après conversion chimique des HO2 grâce à l’ajout de NO. / Peroxy radicals RO2 (with R = H or CxHy) play an important role in the photo-oxidation cycles of the troposphere. They are produced mainly via the atmospheric oxidation of hydrocarbons and carbon monoxide by OH radicals and subsequent reactions with O2. They can further react with NO to produce NO2, witch is an important reaction of tropospheric ozone generation. To understand the mechanism of this tropospheric ozone generation, precise and accurate measurements of ambient peroxy radical concentrations are essential. And not only atmospheric concentration measurements but also atmospheric kinetics studies such as lifetime measurements of peroxy radicals are necessary. Recent publications show big differences between measured peroxy radical concentrations and those calculated with chemical models. These could be caused by missing reaction pathways and uncertainties in reaction yields and rate constants. To investigate these missing reactions and the uncertainties in known peroxy radical reactions via ambient measurements, newly developed two instruments as described below are applied. One is a technique for the selective measurement of atmospheric peroxy radical concentrations of HO2 and RO2 using the PERCA technique. HO2 radicals are selectively removed by using a glass denuder to achieve the selective measurement. The other one is a technique for total HO2 loss rate measurement in the atmosphere by using laser-flash photolysis and LIF detection of HO2. Generated HO2 radicals by laser-flash photolysis react with ambient reactive species such as NOX in the reaction tube. HO2 loss is measured using LIF at 308 nm coupled with chemical conversion with NO.

Advanced healthcare requires novel technologies capable of real-time sensing to long-term health monitoring. One example includes biomarker detection for disease diagnosis and deciding treatment options. But several limitations exist with current technologies; however, the COVID pandemic brought these limitations to a global presence as the authorities struggled to quickly authorize a facile test for the early detection of SARS-CoV-2. An important next step is to research alternate strategies, utilize the current infrastructure available, and build sensors that meet standards the current technologies fail to. One of the strategies involves identifying novel sensing parts. To this end, we turned our attention to bacteria as they provide a plethora of novel sensing parts. Bacteria respond to stimuli using a wide range of biomolecules that include enzymes and transcription factors. Our group reported an optical progesterone biosensor based on a novel progesterone responsive allosteric transcription factor (aTF). Firstly, the electrochemical transduction of the binding affinity between this aTF and its cognate DNA sequence is discussed. The binding and unbinding of aTF-DNA results in an impedance change and is directly proportional to progesterone concentration. The limit of detection is comparable to the optical progesterone sensor and relevant to the physiological ranges of progesterone present in bodily fluids. Secondly, to convert the sensor into a point of care system, the expression of the aTF-enzyme fusion protein that undergoes the binding-unbinding event is discussed. The enzyme in presence of its excess substrate acts as a signal amplifier to track the binding changes. The signal depends on the proximity of the fusion protein to the electrode surface and correlates to the progesterone concentration. As we recover from the deadly COVID pandemic, we realize that early diagnosis is a key pillar of disease containment, in addition to other approaches such as contact tracing, distancing, and personal protective equipment. A truly transformative technology in the fight against future viruses is a rapid and quantitative point-of-care (POC) test with a low limit of detection and a high specificity. To that end, an inverted glucometer technology for the detection of infectious diseases is presented. As a model system, SARS-CoV-2 antigens – nucleocapsid protein, antibodies against it, and an inflammatory biomarker are detected. Antigen of interest is sandwiched between capture and detection reagents with biotin and glucose oxidase tags respectively. Glucose oxidase, a widely used enzyme in glucometers, amplifies the output signal in presence of excess glucose. The following chapters encompass designs, different immobilization techniques, characterization, and optimization methods to develop biosensors that meet requirement standards. This research serves as a platform for development of state of the art technologies for diagnostics applications. / 2025-01-16T00:00:00Z