Thesis--Instituto Tecnologico de La Paz, 1985. / Includes bibliographical references (leaves 46-52).

Visible blue light wavelengths in the 400-470-nm range have been observed to have antimicrobial properties. The purpose of this review article is to delineate the mechanism of action, optimizing conditions, and public health and clinical applications of antimicrobial blue light (aBL) as characterized by the current literature. A widely accepted hypothesis for the mechanism of bacterial inactivation by aBL is that the light causes photoexcitation of endogenous photosensitizers, porphyrins and flavins, which leads to the release of reactive oxygen species that subsequently lead to cell toxicity. Factors that have been observed to be associated with enhanced antimicrobial action include increased duration of exposure, pre-treatment with quinine hydrochloride, and exposure of target bacteria to sub-lethal stress conditions. Studies examining the effect of repetitive exposure to sub-lethal levels of aBL on bacteria show no significant evidence of development of resistance. Additionally, aBL has exhibited the ability to inactivate multidrug-resistant (MDR) bacteria. While studies have also observed aBL to have efficacy in inactivating fungal and viral pathogens, there is a need for further research to elucidate the mechanisms of photoinactivation of fungi and viruses by aBL. Multiple studies have shown that aBL is effective in causing significant CFU reduction in biofilms, an observation that supports the application of aBL for decontamination of surfaces and treatment of localized infections. aBL has demonstrated efficacy in eliminating foodborne pathogens found on food surfaces and exposed surfaces in the food processing environment. Studies applying aBL to decontamination of surfaces in the clinical environment have concluded that it is a viable decontamination practice that shows promise for helping to minimize the spread of healthcare-associated infections (HAIs). Existing literature provides evidence in favor of the application of aBL in clinical contexts such as the treatment of gonococcal infections, eye infections, and otitis media, and in the decontamination of stored platelets and plasma. Studies investigating these clinical applications have demonstrated the efficacy of aBL for inactivating the clinically relevant pathogens, as well as the preservation of normal human cells upon exposure to the doses of light that are lethal to the pathogens. / 2022-11-18T00:00:00Z

No description available.

Volumetric muscle loss (VML) is a debilitating injury which results in full or partial loss of function. Current clinical options utilize tissue grafts and bracing to restore function. Tissue graft implantation oftentimes leads to serious complications, some of which end in graft rejection and thereby necessitate further surgeries and procedures. Polymeric scaffolds show promise as scaffolding systems due to their mechanical properties and overall degradation profiles. Scaffolds need appropriate mechanical properties, 10-60 kPa modulus, and overall degradation times, five days to two weeks, to initiate tissue regeneration. Poly(β-amino ester)s (PBAE), a class of synthetic polymers, act as a safe biocompatible material with overall degradation times that are suitable for healing; however, due to harmful ultraviolet light (UV) irradiation from common crosslinking methods, these scaffold systems cannot be synthesized in vivo. This research presents the development and characterization of blue light (BL) crosslinked PBAEs. BL PBAEs showed vastly higher swelling ratios, 300-400% increase; decreased mechanical strength, an average decrease of 877 kPa in compressive modulus and 431 kPa in tensile modulus; and prolonged degradation patterns, 22% average mass retention. BL PBAEs show mechanical properties and degradation profiles that could be used as a skeletal muscle scaffolds.

Plants absorb CO2 through pores in their leaves called stomata, which are known to open and close in response to myriad environmental and physiological triggers. We demonstrate that blue light inhibits stomatal aperture oscillations in both the guard cells and surrounding tissue layers, whereas these oscillations continue under the influence of red light. This observation of blue light behavior agrees with recent research and suggests another physiological pathway for oscillations.

Organic light emitting diodes (OLEDs) are electronic devices made by sandwitching organic light emissive materials between two electrodes. When voltage is applied across the two conductors, a bright light is generated. The color of the emitting light depends on the band gap of the semiconducting material. The work described here focuses on designing and synthesizing narrow band gap molecular systems derived from fused-arene derivatives for producing organic blue light emitting diodes. Three molecular systems derived from anthracene, pyrene, and carbazole, were designed and synthesized. Two molecular systems of anthracen-9-ylmethyl anthracene-9- carboxylate and pyren-1-ylmethyl 4-bromobenzoate were synthesized through Steglich esterification reaction and the third, pyren-1-ylmethyl 4-(9-hexyl-6-{4-[(pyren-1- ylmethoxy) carbonyl] phenyl}-9H-carbazol-3-yl) benzoate was synthesized by Grignard metathesis followed by Kumada coupling reaction. Structural characterizations were performed using 1H, 13C NMR and FTIR analysis. Photophysical properties of these systems were studied in chloroform (CHCl3) solution using UV-visible and Fluorescence spectroscopies. The absorption and fluorescence emission spectra revealed the potential applicability of these three systems as blue and blue-green emitters for OLEDs. The future work of this project will focus on utilizing these three molecular systems to fabricate OLED devices.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on May 21, 2009. Major professor: Xiaomin Jin. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "March 2009." Includes bibliographical references (p. 80-84). Also available on microfiche.

<p>Aging is associated with a decline in visual function and increased prevalence of ocular disease, correlating with changes in the transcriptome and epigenome of cells in the eye. The extended photoreceptor cell lifespan, in addition to its high metabolic needs due to phototransduction, makes it critical for these neurons to continually respond to the stresses associated with aging by mounting an appropriate gene expression response. My work, in collaboration with fellow lab members and colleagues, has focused on better understanding the regulatory mechanisms that result in age-dependent transcriptional changes in photoreceptors, and if these changes not only correlate with but cause the decrease in function with age. In order to better characterize photoreceptor specific changes my initial work first focused on expanding the gene expression toolkit for eye specific expression. In chapter 1 we describe a previously unnoticed sevenless mutation present in the majority of the TRiP RNAi collection. In chapter 2 we characterized the currently available eye- and photoreceptor-specific binary expression system drivers in <i>Drosophila</i>. Using a luciferase and fluorescent reporter, we characterized the relative expression and cell type-specificity of each driver in the 10-day old adult eye. Also, wecharacterized the expression pattern of these drivers in various developmental stages. We then compared several Gal4 drivers from the Bloomington Drosophila Stock Center (BDSC) including GMR-Gal4, longGMR-Gal4 and Rh1-Gal4 with newly developed Gal4 and QF2 drivers that are specific to different cell types in the adult eye. In addition, we generated drug-inducible Rh1-GSGal4 lines and compared their induced expression with an available GMR-GSGal4 line. Although both lines had significant induction of gene expression measured by luciferase activity, Rh1-GSGal4 was expressed at levels below the detection of the fluorescent reporter by confocal microscopy, while GMR-GSGal4 showed substantial reporter expression in the absence of drug by microscopy. This study systematically characterized and compared a large toolkit of eye- and photoreceptor-specific drivers, while also uncovering some of the limitations of currently available expression systems in the adult eye.</p><p>In chapter 3, we sought to untangle the more general neuronal age-dependent transcriptional signature of photoreceptors with that induced by light stress. To do this, we aged flies or exposed them to various durations of blue light, followed by photoreceptor nuclei-specific transcriptome profiling. Using this approach, we identified genes that are both common and uniquely regulated by aging and light induced stress. Whereas both age and blue light induce expression of DNA repair genes and a neuronal-specific signature of death, both conditions result in downregulation of neurotransmitters important for synaptic transmission. Interestingly, blue light uniquely induced genes that directly counteract the overactivation of the phototransduction signaling cascade. Lastly, unique gene expression changes in aging photoreceptors included the downregulation of genes involved in membrane potential homeostasis and mitochondrial function, as well as the upregulation of immune response genes. We proposed that light stress contributes to the aging transcriptome of photoreceptors, but that there are also other environmental or intrinsic factors involved in age-associated photoreceptor gene expression signatures.</p><p>In chapter 4, we sought to test if age-associated changes in gene expression patterns in the eye directly contribute to the increased risk of retinal degeneration. To do this, we performed a targeted photoreceptor specific RNAi screen in <i>Drosophila </i>to identify gene regulatory factors that result in premature, age-dependent retinal degeneration. From an initial set of 155 RNAi lines each targeting a unique gene and spanning a diverse set of gene regulatory factors, we identified 18 high confidence target genes whose decreased expression in adult photoreceptors leads to premature and progressive retinal degeneration. The 18 target genes were enriched for factors involved in the regulation of transcription initiation, pausing, and elongation, suggesting that these processes are essential for maintaining the health of aging photoreceptors. To identify the genes regulated by these factors, we profiled the photoreceptor transcriptome in a subset of lines. Strikingly, two of the 18 target genes, <i>Spt5</i> and <i>domino</i>, show substantially similar changes in gene expression to those observed with advanced age.</p><p>Together, our data suggests that dysregulation of the mechanisms involved in transcription initiation and elongation plays a key role in shaping the transcriptome of aging photoreceptors. Further, our findings indicate that the age-dependent changes in gene expression not only correlate, but might also contribute to increased risk of retinal degeneration.</p>

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No description available.