Whole document restricted, see Access Instructions file below for details of how to access the print copy. Subscription resource available via Digital Dissertations / Amylin is a 37-amino acid peptide usually cosecreted with insulin from pancreatic islet β-cells. It is implicated in the regulation of normal glucose metabolism and thought to induce pathological features of non-insulin-dependent diabetes mellitus (NIDDM). In particular, human amylin (hA) deposits as islet amyloid, and is associated with the loss of insulin-producing islet β-cells in NIDDM. The biochemical mechanism of hA-evoked death in cultured RINm5F pancreatic islet β-cells has been investigated in this thesis. Synthetic hA but not rat amylin (rA) aggregated in aqueous solution, formed fibrils, and evoked β-cell death in a time- and concentration-dependent manner. The cell death exhibited apoptotic features, including inter-nucleosomal DNA fragmentation, mitochondrial dysfunction, delayed membrane lysis, aurintricarboxylic acid suppression and cell membrane blebbling. Cytotoxicity of hA was inhibited by Congo red (an amyloid-binding dye), 8-37hA fragment (fibril-forming but non-toxic), 1-40βA or 25-35βA (Alzheimer-associated peptide), but neither by sorbitol (inhibitory to hA fibril formation), rA nor its 8-37rA peptide (non-fibril-forming and non-toxic). Preformed large amyloid deposits of hA were less potent in causing β-cell death than small aggregates. These data suggest that hA induces β-cell apoptosis via small aggregates through a possible membrane receptor pathway. Inhibitors of protein and mRNA synthesis did not inhibit hA-evoked apoptosis, but rather enhanced or directly triggered β-cell death during prolonged exposure. Likewise, Ca2+ modulators, which alter intracellular free Ca2+ concentration ([Ca2+]i), failed to prevent hA cytotoxicity and were ultimately cytotoxic themselves. Fura-2 loading and 45Ca2+ uptake studies indicated that hA did not mobilise intracellular Ca2+ during its toxicity. These results indicate a protein synthesis- and Ca2+-independent process of hA toxicity RINm5F islet β-cells. The studies reported in this thesis have established a new in vitro model of hA-evoked apoptosis using cultured RINm5F pancreatic islet β-cells. A new model of NIDDM pathogenesis is presented and discussed.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. Subscription resource available via Digital Dissertations / Amylin is a 37-amino acid peptide usually cosecreted with insulin from pancreatic islet β-cells. It is implicated in the regulation of normal glucose metabolism and thought to induce pathological features of non-insulin-dependent diabetes mellitus (NIDDM). In particular, human amylin (hA) deposits as islet amyloid, and is associated with the loss of insulin-producing islet β-cells in NIDDM. The biochemical mechanism of hA-evoked death in cultured RINm5F pancreatic islet β-cells has been investigated in this thesis. Synthetic hA but not rat amylin (rA) aggregated in aqueous solution, formed fibrils, and evoked β-cell death in a time- and concentration-dependent manner. The cell death exhibited apoptotic features, including inter-nucleosomal DNA fragmentation, mitochondrial dysfunction, delayed membrane lysis, aurintricarboxylic acid suppression and cell membrane blebbling. Cytotoxicity of hA was inhibited by Congo red (an amyloid-binding dye), 8-37hA fragment (fibril-forming but non-toxic), 1-40βA or 25-35βA (Alzheimer-associated peptide), but neither by sorbitol (inhibitory to hA fibril formation), rA nor its 8-37rA peptide (non-fibril-forming and non-toxic). Preformed large amyloid deposits of hA were less potent in causing β-cell death than small aggregates. These data suggest that hA induces β-cell apoptosis via small aggregates through a possible membrane receptor pathway. Inhibitors of protein and mRNA synthesis did not inhibit hA-evoked apoptosis, but rather enhanced or directly triggered β-cell death during prolonged exposure. Likewise, Ca2+ modulators, which alter intracellular free Ca2+ concentration ([Ca2+]i), failed to prevent hA cytotoxicity and were ultimately cytotoxic themselves. Fura-2 loading and 45Ca2+ uptake studies indicated that hA did not mobilise intracellular Ca2+ during its toxicity. These results indicate a protein synthesis- and Ca2+-independent process of hA toxicity RINm5F islet β-cells. The studies reported in this thesis have established a new in vitro model of hA-evoked apoptosis using cultured RINm5F pancreatic islet β-cells. A new model of NIDDM pathogenesis is presented and discussed.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. Subscription resource available via Digital Dissertations / Amylin is a 37-amino acid peptide usually cosecreted with insulin from pancreatic islet β-cells. It is implicated in the regulation of normal glucose metabolism and thought to induce pathological features of non-insulin-dependent diabetes mellitus (NIDDM). In particular, human amylin (hA) deposits as islet amyloid, and is associated with the loss of insulin-producing islet β-cells in NIDDM. The biochemical mechanism of hA-evoked death in cultured RINm5F pancreatic islet β-cells has been investigated in this thesis. Synthetic hA but not rat amylin (rA) aggregated in aqueous solution, formed fibrils, and evoked β-cell death in a time- and concentration-dependent manner. The cell death exhibited apoptotic features, including inter-nucleosomal DNA fragmentation, mitochondrial dysfunction, delayed membrane lysis, aurintricarboxylic acid suppression and cell membrane blebbling. Cytotoxicity of hA was inhibited by Congo red (an amyloid-binding dye), 8-37hA fragment (fibril-forming but non-toxic), 1-40βA or 25-35βA (Alzheimer-associated peptide), but neither by sorbitol (inhibitory to hA fibril formation), rA nor its 8-37rA peptide (non-fibril-forming and non-toxic). Preformed large amyloid deposits of hA were less potent in causing β-cell death than small aggregates. These data suggest that hA induces β-cell apoptosis via small aggregates through a possible membrane receptor pathway. Inhibitors of protein and mRNA synthesis did not inhibit hA-evoked apoptosis, but rather enhanced or directly triggered β-cell death during prolonged exposure. Likewise, Ca2+ modulators, which alter intracellular free Ca2+ concentration ([Ca2+]i), failed to prevent hA cytotoxicity and were ultimately cytotoxic themselves. Fura-2 loading and 45Ca2+ uptake studies indicated that hA did not mobilise intracellular Ca2+ during its toxicity. These results indicate a protein synthesis- and Ca2+-independent process of hA toxicity RINm5F islet β-cells. The studies reported in this thesis have established a new in vitro model of hA-evoked apoptosis using cultured RINm5F pancreatic islet β-cells. A new model of NIDDM pathogenesis is presented and discussed.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. Subscription resource available via Digital Dissertations / Amylin is a 37-amino acid peptide usually cosecreted with insulin from pancreatic islet β-cells. It is implicated in the regulation of normal glucose metabolism and thought to induce pathological features of non-insulin-dependent diabetes mellitus (NIDDM). In particular, human amylin (hA) deposits as islet amyloid, and is associated with the loss of insulin-producing islet β-cells in NIDDM. The biochemical mechanism of hA-evoked death in cultured RINm5F pancreatic islet β-cells has been investigated in this thesis. Synthetic hA but not rat amylin (rA) aggregated in aqueous solution, formed fibrils, and evoked β-cell death in a time- and concentration-dependent manner. The cell death exhibited apoptotic features, including inter-nucleosomal DNA fragmentation, mitochondrial dysfunction, delayed membrane lysis, aurintricarboxylic acid suppression and cell membrane blebbling. Cytotoxicity of hA was inhibited by Congo red (an amyloid-binding dye), 8-37hA fragment (fibril-forming but non-toxic), 1-40βA or 25-35βA (Alzheimer-associated peptide), but neither by sorbitol (inhibitory to hA fibril formation), rA nor its 8-37rA peptide (non-fibril-forming and non-toxic). Preformed large amyloid deposits of hA were less potent in causing β-cell death than small aggregates. These data suggest that hA induces β-cell apoptosis via small aggregates through a possible membrane receptor pathway. Inhibitors of protein and mRNA synthesis did not inhibit hA-evoked apoptosis, but rather enhanced or directly triggered β-cell death during prolonged exposure. Likewise, Ca2+ modulators, which alter intracellular free Ca2+ concentration ([Ca2+]i), failed to prevent hA cytotoxicity and were ultimately cytotoxic themselves. Fura-2 loading and 45Ca2+ uptake studies indicated that hA did not mobilise intracellular Ca2+ during its toxicity. These results indicate a protein synthesis- and Ca2+-independent process of hA toxicity RINm5F islet β-cells. The studies reported in this thesis have established a new in vitro model of hA-evoked apoptosis using cultured RINm5F pancreatic islet β-cells. A new model of NIDDM pathogenesis is presented and discussed.

Thesis (Ph.D.)--Lehigh University, 2007. / Adviser: Samir N. Ghadiali.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6252. Adviser: Enrico Gratton. Includes bibliographical references (leaves 80-87) Available on microfilm from Pro Quest Information and Learning.

Although techniques in molecular imaging have advanced considerably over the past several decades, there remain numerous categories of biological molecular targets that are refractory to straightforward imaging. Among these is molecular oxygen, which is vital to a host of physiological as well as pathological processes, as well as the amorphous pigment pheomelanin, which may play a formerly unappreciated role in melanoma carcinogenesis. This thesis describes two related bodies of work that advance techniques in oxygen and pheomelanin imaging, respectively. First, inspired by a desire to understand how hypoxia affects cancer chemotherapy on a cellular level, we designed and synthesized a novel oxygen-sensitive, dendritic nanoconstruct that is capable of spontaneously penetrating through hundreds of microns of multiple cellular layers. After demonstrating our nanoconjugate's oxygen sensitivity using time-domain phosphorescence lifetime measurements, we demonstrate that it retains its oxygen sensitivity in a 3D spheroid in vitro model of ovarian cancer through the use of a custom-made, near infrared-optimized confocal phosphorescence imaging system. Drawing from this approach, we then describe the fabrication and calibration of a separate oxygen-sensing bandage platform for use in wound-healing applications, and demonstrate its use in ex vivo and in vivo animal systems. The second body of work describes the use of non-linear four-wave mixing techniques to facilitate straightforward imaging of the molecular pigment pheomelanin. Recent findings suggest that pheomelanin may play a previously unappreciated role in melanoma carcinogenesis, even in the complete absence of an ultraviolet light insult. However, due to its pale color, pheomelanin is difficult to visualize against a skin background, making its study challenging. After constructing a femtosecond-pulsed coherent anti-Stokes Raman scatter (CARS) microscopy imaging system, we use imaging and spectroscopy to provide proof-of-concept that pheomelanin can be imaged through a combination of CARS microscopy and electronically-enhanced four-wave mixing. We then use our non-linear imaging system to specifically observe pheomelanin in isolated "redhead" mouse melanocytes, and show through an siRNA gene knock-down strategy that our system can be used to observe changes in pheomelanin signal upon modification of biological pathways known to affect pheomelanin synthesis.

Metabolic tumor profiling illustrates the spatiotemporal distribution of key analytes to assess and quantify tumor growth, metabolism, and response to therapy. Since the tumor microenvironment is characterized by hypoxia, the ability to track and quantify changes in oxygen concentration as a function of disease progression or therapy is crucial to the advancement of targeted therapeutics. The ability to monitor these changes necessitates the development of non-invasive sensors that are small enough to penetrate into tumor tissue and monitor dynamic changes with high resolution in real time. To address this challenge, this thesis details the design, synthesis, and characterization of optical oxygen sensors that combine a fluorescent semiconductor quantum dot (QD) with a Pd(II) porphyrin or Au(III) corrole as the oxygen-responsive phosphor. In these constructs, the QD donor serves as a photon antenna and transfers the absorbed energy to the appended porphyrin or corrole acceptor by Förster resonance energy transfer (FRET). The triplet state of the phosphor is quenched by molecular oxygen and is responsive over the biologically relevant 0–160 Torr O2 range. These donor–acceptor conjugates are prepared by self-assembly in organic solvents or micelle encapsulation in aqueous media. The Pd(II) porphyrin micelles were then used for in vivo imaging and oxygen sensing in murine models. In the search for alternative phosphors for optical oxygen sensing, a variety of metallocorrole complexes were prepared. Although these derivatives were not phosphorescent, they have provided insight into the photophysics, electronic structure, and photochemistry of corroles, as described in the second half of this thesis. The photophysical properties of free-base, Au(III), Sb(III), and Sb(V) corroles were interrogated. The role of corrole as a non-innocent ligand was then explored for copper and silver complexes. Analysis of these compounds reveals that copper complexes are Cu(II) corrole radical cations, while the silver analogs are authentic Ag(III) complexes. Finally, the photochemistry of Sb(V) corroles was studied for both C–H activation of organic substrates and halogen evolution as a potential solar fuel. Together, these studies examine fundamental photophysics and electronic structure, as well as provide examples where these complexes may be used to mediate photochemical transformations. / Chemistry and Chemical Biology

Respiratory sounds are of significance as they provide valuable information on the health of the respiratory system. Sounds emanating from the respiratory system are uneven, and vary significantly from one individual to another and for the same individual over time. In and of themselves they are not a direct proof of an ailment, but rather an inference that one exists. Auscultation diagnosis is an art/skill that is acquired and honed by practice; hence it is common to seek confirmation using invasive and potentially harmful imaging diagnosis techniques like x-rays. This research focuses on developing an automated auscultation diagnostic system that overcomes the limitations inherent in traditional auscultation techniques. The system uses a front end sound signal filtering module that uses adaptive Neural Networks (NN) noise cancellation to eliminate spurious sound signals like those from the heart, intestine, and ambient noise. The core diagnosis module of the system is capable of identifying lung sounds from non-lung sounds, normal lung sounds from abnormal ones, and identifying wheezes from crackles as indicators of different ailments. Furthermore, the system is capable of identifying the location of different infected sites of the diseased lungs. An approach for generating virtual patients auscultation sounds by isolating the adventitious signals from lung sounds and injecting them into healthy lung sounds has been developed Forty distinct virtual patients were generated and used to test the performance of the identification and localization modules of the system. Test results using real and virtual auscultation sounds show the high efficacy of the conceived system.

No description available.