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The goal of this thesis is to study the potential of optical spectroscopy as a clinical diagnostic tool for melanoma and nonmelanoma skin cancer. Skin cancer is the most common cancer in the United States. Like most cancers, early diagnosis and treatment improves patient prognosis for both melanoma and nonmelanoma skin cancer. However, current “gold standard” for diagnosis is invasive, costly and time-consuming. A diagnostic procedure consists of a clinical examination of the suspicious lesion, followed by biopsy and histopathology, with an additional turnaround time of approximately one week. There is a need for an accurate, objective, noninvasive, and faster method to aid physician in diagnosing cancerous lesions, increasing diagnosis accuracy while preventing unnecessary biopsies. We propose Spectral Diagnosis, a system capable of noninvasive in vivo spectroscopic examination of human skin. The research objectives are: (1) Probe pressure effects on in vivo spectroscopy measurements of human skin, (2) Clinical trial of Spectral Diagnosis, (3) Design, construction, and characterization of a confocal Raman microspectroscope. Spectral Diagnosis utilizes an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. We identified short term and light probe pressure effects to be minimal on diagnostic parameters, and should not negatively influence diagnostic performance. We conducted a clinical trial at the University of Texas MD Anderson Cancer Center, and our results show that principal components from three spectroscopy modalities (diffuse reflectance spectroscopy, laser induced fluorescence spectroscopy, and Raman spectroscopy) provide excellent melanoma and nonmelanoma skin cancer diagnosis. We also constructed and characterized a Raman microspectroscope, with the goal of developing a physiological-based fitting model to better understand the analysis of in vivo Raman spectroscopy data from human skin tissue. / text

One of the main problems in healthcare is the loss or failure of organs or tissues resulting from diseases, post-surgery complications, trauma or organ failure. As a result of tissue and organ shortage, there is a need for biomaterials designed to promote tissue regeneration resulting in good quality repair of tissues or organs, to maintain or repair biological function. Collagen, as one of the main proteins in the human body, has been extensively used in the development of biomaterials which can be used as tissue substitutes or can assist in tissue regeneration. Before commercialisation is allowed all biomaterials must prove to be functional and suitable for clinical use. Therefore, the evaluation of biomaterials requires rigorous and relevant testing. Biomaterials must be able to perform with an appropriate host response in a specific application. Tests must provide information to understand the host response, long-term outcome and issues pertaining to these. In the research reported in this thesis, an acellular porcine derived cross-linked collagen-based biomaterial (Permacol surgical implant) was analysed with a wide range of evaluation and compared to acellular noncross-linked and cellular, naturally cross-linked, equivalents. These matrices were characterized relating to their structure, composition and mechanical and biochemical properties. In addition, biological characterisation was performed through several studies designed to evaluate and compare biological responses in vitro, as well as in situ assessment of biocompatibility and effectiveness as a repair material and as bulking tissue. Permacol surgical implant was shown to be biocompatible, effective and efficient when used as bulking tissue and for soft tissue repair; furthermore, this biomaterial was resistant to enzymatic digestion and tolerant to bacterial presence suggesting that it could be used in some complicated clinical situations.

Polymer scaffold use has become commonplace in tissue engineering strategies. Scaffolds provide sturdy interfaces that securely anchor tissue engineered constructs to their designated locations. Researchers have used scaffolds to provide support to developing tissues as well as a growth template to aid the development of the desired phenotypic structure. In addition to using scaffolds for their mechanical support, scaffolds can be used as a diagnostic tool by attaching sensors. Strain gauge sensors have been attached to scaffolds to monitor compression and elongation. These polybutylterphalate (PBT) scaffolds were used in a cartilage tissue-engineering project for femoral cartilage repair. The aim of this project was to measure native cartilage pressure in normal canine stifle joints using strain gauge scaffolds. By using pressure sensitive films to confirm joint surface pressures determined with strain gauge measurements, "sensate" scaffolds were created to be able to provide in vivo joint loading measurements. An understanding of the in vivo pressures in the menisco-femoral joint space will facilitate the development of tissue engineered cartilage by determining chondrocyte mechanical triggers as well as helping define reasonable expectations for engineered articular cartilage tissue that is required for successful cartilage repair.

As part of a project to see whether potatoes with a low glycemic-index (GI) could be developed through plant breeding, the GI values of 4 new potato varieties differing in starch structure was determined in 3 studies over 2 years in human subjects. Since cooking and cooling affects starch structure the potatoes were studied both freshly cooked (boiled) and cooled. The first study showed that cooling reduced the GI of two varieties by 40-50% but had no effect in the others (treatment × variety interaction, p=0.024), an effect which was confirmed in study 2. Differences in GI were readily explained by differences in starch structure or in-vitro digestion rate. Carbohydrate malabsorption increased from 3 to 5% upon cooling, not enough to account for the reduced GI. It is concluded that the effect on GI of cooling cooked potatoes varies in different varieties. Further research is needed to understand the mechanism.

As part of a project to see whether potatoes with a low glycemic-index (GI) could be developed through plant breeding, the GI values of 4 new potato varieties differing in starch structure was determined in 3 studies over 2 years in human subjects. Since cooking and cooling affects starch structure the potatoes were studied both freshly cooked (boiled) and cooled. The first study showed that cooling reduced the GI of two varieties by 40-50% but had no effect in the others (treatment × variety interaction, p=0.024), an effect which was confirmed in study 2. Differences in GI were readily explained by differences in starch structure or in-vitro digestion rate. Carbohydrate malabsorption increased from 3 to 5% upon cooling, not enough to account for the reduced GI. It is concluded that the effect on GI of cooling cooked potatoes varies in different varieties. Further research is needed to understand the mechanism.

No description available.

<p>The ability of young children to vocally imitate the speech of adults is critical for speech learning. Vocal imitation requires exposure to an external auditory model and the use of auditory feedback to adaptively modify vocal output to match the model. Despite the importance of vocal imitation to human communication and social behavior, it remains unclear how these two types of sensory experience, model exposure and feedback, act on sensorimotor networks controlling the learning and production of learned vocalizations. Using a combination of longitudinal in vivo imaging of neuronal structure and electrophysiological measurements of neuronal function, I addressed the questions of where, when, and how these two types of sensory experience act on sensorimotor neurons important to singing and song learning in zebra finches. The major finding of these experiments is that synaptic inputs onto neurons in HVC, a sensorimotor nucleus important to singing and song learning, are sensitive to tutor song experience and deafening. Thus, these findings for the first time link auditory experiences important to vocal imitation to synaptic reorganization in sensorimotor neurons important to behavior.</p> / Dissertation

The presence of off-flavor compounds in fish represents one of the significant economic problems encountered in aquaculture. These off-flavor compounds are due to the absorption of substances produced by microorganisms. Currently, a number of strategies have been employed to prevent or limit the growth of these microorganisms in recirculating aquaculture system. Therefore, it is important to evaluate the effectiveness of these strategies by monitoring the concentrations of off-flavor compounds in fish. In-vivo solid phase microextraction (SPME), a rapid and simple sample preparation method, allows the monitoring of concentrations of off-flavor compounds in live fish. In this research, geosmin and 2-methylisoborneol (2-MIB), which are produced by cyanobacteria and actinomycetes being the major sources for “earthy” and “muddy” flavors in fish, were selected as representatives. In order to accurately quantify these compounds in fish muscle, two kinetic calibration methods, on-fibre standardization and measurement using pre-determined extraction rate, were used. Results obtained were validated by traditional methods. The detection limit of in-vivo SPME in fish muscle was 0.12 ng/g for geosmin and 0.21 ng/g for 2-MIB, both below the human sensory threshold. Additionally, the binding effect of geosmin and 2-MIB in fish muscle was investigated in details. Facilitated by the agarose gel model, it was proven that binding did not impact the extraction rate under the pre-determined sampling time. Furthermore, an optional sampling position was undertaken by inserting the fibre into the fat tissue found under the fish belly, the results indicating that this method could decrease extraction time by up to two-thirds of its usual time.

Zugl.: Dresden, Techn. Univ., Diss., 2007