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- Title
- REGULATION OF APOPTOTIC ALKALINIZATION THROUGH PHOSPHORYLATION OF SODIUM HYDROGEN EXCHANGER VIA P38 MITOGEN ACTIVATED PROTEIN KINASE.
- Creator
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GRENIER, AMY, KHALED, ANNETTE, University of Central Florida
- Abstract / Description
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Regulation of intracellular pH is responsible for many cellular processes, such as metabolism, cell cycle progression, and apoptosis. Many chemotherapeutic agents work by inducing target cells to undergo apoptosis, a cell death process still poorly understood. Previous studies demonstrated that a rise in intracellular pH activated apoptotic proteins leading to cytochrome C release. This "apoptotic alkalinization" occurred upon activation of the plasma membrane protein, sodium hydrogen...
Show moreRegulation of intracellular pH is responsible for many cellular processes, such as metabolism, cell cycle progression, and apoptosis. Many chemotherapeutic agents work by inducing target cells to undergo apoptosis, a cell death process still poorly understood. Previous studies demonstrated that a rise in intracellular pH activated apoptotic proteins leading to cytochrome C release. This "apoptotic alkalinization" occurred upon activation of the plasma membrane protein, sodium hydrogen exchanger-1 (NHE1), whose activity is regulated by the stress kinase p38 MAPK. In previous studies, upon cytokine withdrawal from cytokine-dependent lymphocytes induced the activity of the p38 MAP kinase which then phosphorylated the C-terminus of NHE1. To identify the p38 MAPK phosphorylation sites on NHE1, in vitro p38 MAP kinase assays coupled to deletion analysis of NHE1 and mass spectrometry, identified four possible p38 MAPK phosphorylation sites. To establish that NHE1 causes apoptotic alkalinization and determine whether the identified phosphorylation sites on NHE1 are functionally significant, we used PCR site directed mutagenesis to mutate T717, S722, S725, and S728 on the C-terminus of NHE1. Stable NHE1 deficient cell lines, expressing wild type (WT) NHE or the four mutated sites (F4MUTNHE), were assessed for apoptotic alkalinization using the pH-sensitive fluorescent protein, destabilized YFP. Our results show that NHE1 is required for apoptotic alkalinization, since expression of WT NHE restored alkalinization in an NHE deficient cell line, and that this process requires the phosphorylation of the p38 MAPK target sites, since mutation of all four sites prevented the apoptotic alkalinization response.
Show less - Date Issued
- 2006
- Identifier
- CFE0001078, ucf:46768
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001078
- Title
- THE EFFECTS OF PH ON ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL (EBPR) WITH PROPIONIC ACID AS THE DOMINANT VOLATILE FATTY ACID (VFA).
- Creator
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malekjahani, seyed, Randall, Andrew, University of Central Florida
- Abstract / Description
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pH control is a tool to improve some aspects of Enhanced Biological Phosphorus Removal (EBPR) process. Filipe et al (2001a, 2001b, and 2001c) found strong evidence that the stability of EBPR systems can be improved by increasing the pH of the anaerobic zone, thereby creating conditions where phosphorus-accumulating organisms (PAOs) are able to take up acetate faster than glycogen-accumulating organisms (GAOs). They explained this observation by comparing the growth rate of phosphorus...
Show morepH control is a tool to improve some aspects of Enhanced Biological Phosphorus Removal (EBPR) process. Filipe et al (2001a, 2001b, and 2001c) found strong evidence that the stability of EBPR systems can be improved by increasing the pH of the anaerobic zone, thereby creating conditions where phosphorus-accumulating organisms (PAOs) are able to take up acetate faster than glycogen-accumulating organisms (GAOs). They explained this observation by comparing the growth rate of phosphorus-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) and found that pH has little effect on PAOs growth rate but adversely affects GAOs growth rate when it increases (at pH values greater than 7.25, PAOs would take acetate faster than GAOs would). They used synthetic wastewater rich in acetic acid. In this study, we used real wastewater and the dominant volatile fatty acid available to microorganisms was propionic acid in continuous EBPR system. It was found that lower anaerobic zone pH (6.5 vs. 7.2) reduced the anaerobic P release both on an MLVSS specific basis and also on a non-specific (absolute value for the process) basis. In addition, the observed yield was significantly decreased. Aerobic P uptake was lower in the low-pH system (on a non-specific basis) due to the lower observed yield, and thus lower MLVSS concentration. Net P uptake was hard to interpret because of the effect of P release in the secondary clarifier of Train 2 (high pH). However, on a specific basis it was clear that net P uptake was either equal or better in the low-pH system regardless of how the secondary clarifier data was interpreted. Carbon transformations were not impacted in as consistent a fashion as anaerobic P release was. On a specific basis, PHA content remained unchanged although the PHV/PHB ratio was impacted with much lower PHV content in the low-pH system. Glycogen content and the amount of labile glycogen (delta glycogen) were higher in the low-pH system, in spite of the fact that MLVSS P content did not decrease. However, due to the impact of the low observed yield at low pH, absolute values resulted in higher PHA content for the process reactors as a whole, higher glycogen content, and unchanged labile glycogen. Low pH resulted in increased biomass P content, however the lower observed yield offset this on a process basis so that effluent P levels were nearly equal. So low pH improved P removal on a specific basis, but not on a process basis. Since it is unknown if the low observed yield is repeatable, and due to the impact of the secondary clarifier in the high pH system, it cannot be concluded that the effect of low pH on net P removal would be similar in other EBPR systems.
Show less - Date Issued
- 2006
- Identifier
- CFE0001433, ucf:47042
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001433
- Title
- HELICAL PACKING REGULATES STRUCTURAL TRANSITIONS IN BAX.
- Creator
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Tschammer, Nuska, Khaled, Annette, University of Central Florida
- Abstract / Description
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Apoptosis is essential for development and the maintenance of cellular homeostasis and is frequently dysregulated in disease states. Proteins of the BCL-2 family are key modulators of this process and are thus ideal therapeutic targets. In response to diverse apoptotic stimuli, the pro-apoptotic member of BCL-2 family, BAX, redistributes from the cytosol to the mitochondria or endoplasmic reticulum and primes cells for death. The structural changes that enable this lethal protein to...
Show moreApoptosis is essential for development and the maintenance of cellular homeostasis and is frequently dysregulated in disease states. Proteins of the BCL-2 family are key modulators of this process and are thus ideal therapeutic targets. In response to diverse apoptotic stimuli, the pro-apoptotic member of BCL-2 family, BAX, redistributes from the cytosol to the mitochondria or endoplasmic reticulum and primes cells for death. The structural changes that enable this lethal protein to transition from a cytosolic form to a membrane-bound form remain poorly understood. Elucidating this process is a necessary step in the development of BAX as a novel therapeutic target for the treatment of cancer, as well as autoimmune and neurodegenerative disorders. A three-part study, utilizing computational modeling and biological assays, was used to examine how BAX, and similar proteins, transition to membranes. The first part tested the hypothesis that the C-terminal α9 helix regulates the distribution and activity of BAX by functioning as a "molecular switch" to trigger conformational changes that enable the protein to redistribute from the cytosol to mitochondrial membrane. Computational analysis, tested in biological assays, revealed a new finding: that the α9 helix can dock into a hydrophobic groove of BAX in two opposite directions – in a self-associated, forward orientation and a previously, unknown reverse orientation that enables dimerization and apoptosis. Peptides, made to mimic the α9-helix, were able to induce the mitochondrial translocation of BAX, but not when key residues in the hydrophobic groove were mutated. Such findings indicate that the α9 helix of BAX can function as a "molecular switch" to mediate occupancy of the hydrophobic groove and regulate the membrane-binding activity of BAX. This new discovery contributes to the understanding of how BAX functions during apoptosis and can lead to the design of new therapeutic approaches based on manipulating the occupancy of the hydrophobic groove. The second and third parts of the study used computational modeling to examine how the helical stability of proteins relates to their ability to functionally transition. Analysis of BAX, as a prototypical transitioning protein, revealed that it has a broad variation in the distribution of its helical interaction energy. This observation led to the hypothesis tested, that proteins which undergo 3D structural transitions during execution of their function have broad variations in the distribution of their helical interaction energies. The result of this study, after examination of a large group of all-alpha proteins, was the development of a novel, predictive computational method, based on measuring helical interactions energies, which can be used to identify new proteins that undergo structural transitioning in the execution of their function. When this method was used to examine transitioning in other members the BCL-2 family, a strong agreement with the published experimental findings resulted. Further, it was revealed that the binding of a ligand, such as a small peptide, to a protein can have significant stabilizing or destabilizing influences that impact upon the activation and function of the protein. This computational analysis thus contributes to a better understanding of the function and regulation of the BCL-2 family members and also offers the means by which peptide mimics that modulate protein activity can be designed for testing in therapeutic endeavors.
Show less - Date Issued
- 2007
- Identifier
- CFE0001865, ucf:47392
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001865
- Title
- SLURRY CHEMISTRY EFFECTS ON COPPER CHEMICAL MECHANICAL PLANARIZATION.
- Creator
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Luo, Ying, Desai, Vimal, University of Central Florida
- Abstract / Description
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ABSTRACTChemical-mechanical Planarization (CMP) has emerged as one of the fastest-growing processes in the semiconductor manufacturing industry, and it is expected to show equally explosive growth in the future (Braun, 2001). The development of CMP has been fueled by the introduction of copper interconnects in microelectronic devices. Other novel applications of CMP include the fabrications of microelectromechanical systems (MEMS), advanced displays, three dimensional systems, and so on ...
Show moreABSTRACTChemical-mechanical Planarization (CMP) has emerged as one of the fastest-growing processes in the semiconductor manufacturing industry, and it is expected to show equally explosive growth in the future (Braun, 2001). The development of CMP has been fueled by the introduction of copper interconnects in microelectronic devices. Other novel applications of CMP include the fabrications of microelectromechanical systems (MEMS), advanced displays, three dimensional systems, and so on (Evans, 2002). CMP is expected to play a key role in the next-generation micro- and nanofabrication technologies (Singh, et al., 2002).Despite the rapid increase in CMP applications, the fundamental understanding of the CMP process has been lacking, particularly the understanding of the wafer-slurry-pad interactions that occur during the CMP process. Novel applications of CMP are expected to expand to materials that are complex chemically and fragile mechanically. Thus, fundamental understanding and improvement of slurry design for CMP is the key to the development of sophisticated next-generation CMP processes.Slurry performance for CMP can be determined by several output parameters including removal rate, global planarity, surface topography, and surface defectivity. To achieve global planarity, it is essential to form a very thin passivating surface layer (<2 nm) that is subsequently removed by the mechanical component of the slurry (Kaufman et al., 1991) or by combined chemo-mechanical effects (Tamboli, 2000). Chemical additives like hydrogen peroxide (H2O2), potassium ferricyanide, and ferric chloride are added to slurries as oxidizers in order to form a desirable surface layer. Other chemical additives such as inhibitors (e.g. benzotriazole) and complexing agents (e.g. ammonia) are added to the copper slurry in order to modify the oxide layer. That the removal rate of the thin surface layer is greater at the highest regions of the wafer surface than at the lowest regions leads to surface planarity.In this study, various complexing agents and inhibitors are combined to form slurry chemistry for copper CMP processing in H2O2 based slurries at pH values ranging from 2 to 10. Two complexing agents (glycine and Ethylenediamine) and one inhibitor (3-amino-1, 2, 4-triazole) were selected as slurry constituents for detailed chemical synergistic effect study because they showed good materials removal and surface planarity performances.To understand the fundamental mechanisms involved in copper CMP process with the afore-mentioned slurry chemical formations, various techniques, such as electrochemical testing techniques (including potentiodynamic polarization and electrochemical impedance spectroscopy), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM), were applied. As a result, guidelines for optimized slurry chemical formulation were arrived at and the possible mechanisms of surface-chemical-abrasive interactions were determined. From applications point of view, this study serves as a guide for further investigations in pursuing highly effective slurry formulations for copper/low-k interconnect applications.
Show less - Date Issued
- 2004
- Identifier
- CFE0000120, ucf:46195
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000120
- Title
- SYNTHESIS OF BIOCOMPATIBLE ANTIOIXIDANT POLYMER COATED CERIUM OXIDE NANOPARTICLES, ITS OXIDASE LIKE BEHAVIOR AND CELLULAR UPTAKE STUDIES.
- Creator
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Asati, Atul, Perez, J Manuel, University of Central Florida
- Abstract / Description
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Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water...
Show moreCerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant giving cytoprotection to normal cell lines against hydrogen peroxide and nitric oxide radical but not to cancer cells. Moreover, cerium oxide nanoparticle also exhibits unique oxidase-like activity at acidic pH oxidizing a series of organic compound without the need of hydrogen peroxide. Based on these results, we have designed an immunoassay in which folate-conjugated cerium oxide nanoparticles provide dual functionality by binding to folate expressing cancer cells and facilitating detection by catalytic oxidation of sensitive colorimetric substrates (dyes). Finally, we have shown that the polymer coated cerium oxide nanoparticles shows distinct toxicity depending upon their subcellular localization based on uptake studies using DiI loaded cerium oxide nanoparticles. In these results, we have found that cerium oxide nanoparticles entrapped into lysosomes are more toxic as opposed to when they are localized in the cytoplasm.Overall we propose that the polymer coated cerium oxide nanoparticles displays selective antioxidant property, oxidase-like activity, and cytotoxicity to biological systems depending upon its pH environment.
Show less - Date Issued
- 2009
- Identifier
- CFE0002924, ucf:47998
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002924
- Title
- Reducing Sulfuric Acid Pretreatment in a Nanofiltration Process Treating Surficial Groundwater.
- Creator
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Higgins, Carlyn, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, University of Central Florida
- Abstract / Description
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Nanofiltration (NF) is a pressure driven membrane process employed in drinking water treatment that requires pretreatment for reliable operation. The objective of this research was to determine if NF membranes can proficiently operate with a decreased or eliminated dose of sulfuric acid pretreatment. When used as pretreatment, sulfuric acid prevents calcium carbonate scaling on NF membranes, yet is costly, hazardous, and imparts high sulfate concentrations to NF feed and concentrate streams....
Show moreNanofiltration (NF) is a pressure driven membrane process employed in drinking water treatment that requires pretreatment for reliable operation. The objective of this research was to determine if NF membranes can proficiently operate with a decreased or eliminated dose of sulfuric acid pretreatment. When used as pretreatment, sulfuric acid prevents calcium carbonate scaling on NF membranes, yet is costly, hazardous, and imparts high sulfate concentrations to NF feed and concentrate streams. To conduct this research, a 0.324 million gallon per day (MGD) NF pilot plant was operated for 3,855 run-hours at a flux rate of 15 gallons per square foot-day. The NF pilot unit's process performance, productivity, and water quality were monitored while the sulfuric acid dose was gradually decreased, controlled by monitoring pH that ranged from pH 6.5 (80 mg/L sulfuric acid dose) to pH 7.0 (no sulfuric acid dose). NF pilot productivity, as measured by specific flux, was found to decline when sulfuric acid was eliminated by 2.33 percent, 9.61 percent, and 4.08 percent in the first stage, second stage, and total pilot system, respectively, with no distinguishable increase in pressure drop. Noticeable water quality trends include approximately 75 percent sulfate decrease in feed and concentrate streams, and 20 percent increase of calcium hardness and alkalinity in the permeate stream. After piloting, superimposed elemental imaging analysis revealed that the second stage, tail-end membrane surface was fouled with iron disulfide, calcium carbonate, clay, and natural organic matter. However, flux recovered to normal operating conditions after a membrane cleaning was performed. Results of the pilot study indicated that sulfuric acid could be eliminated from the full-scale NF pretreatment process; however, membrane cleaning frequencies could increase. If applied to the full-scale NF process, elimination of sulfuric acid pretreatment would reduce annual chemical costs by over $70,000.
Show less - Date Issued
- 2017
- Identifier
- CFE0007287, ucf:52148
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007287
- Title
- Novel Photodynamic Cancer Therapy Agent and Biochemical Phosphate Sensor Based on Nanomaterials.
- Creator
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Fadhel, Alaa, Campiglia, Andres, Belfield, Kevin, Harper, James, Koculi, Eda, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
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Biochemical research and clinical studies have revolutionized the field of medicine in both diagnosis and therapy. Researchers in the field of biochemistry and biotechnology are using nanomaterials in different applications to develop devices and materials that offer benefits to both patients and the health care industry. These include biochemical sensors, enzyme encapsulation, biomarkers, and drug delivery improvements for the treatment of cancer. This dissertation focuses on investigating...
Show moreBiochemical research and clinical studies have revolutionized the field of medicine in both diagnosis and therapy. Researchers in the field of biochemistry and biotechnology are using nanomaterials in different applications to develop devices and materials that offer benefits to both patients and the health care industry. These include biochemical sensors, enzyme encapsulation, biomarkers, and drug delivery improvements for the treatment of cancer. This dissertation focuses on investigating two biochemical aspects using nanomaterials; namely therapy and clinical diagnosis.For therapy purposes, Silica nanoparticles were used as drug delivery system to develop a new photodynamic cancer therapy agent photo-acid generator (PAG) that selectively induces necrotic cell death of cancer cells. The developed PAG is oxygen-independent and - when excited at specific wavelengths - drops the pH within the lysosome of cancer cells to produce apoptosis/necrosis. It was specifically designed for in vivo applications and conjugated with synthesized, highly monodispersed silica nanoparticles (Si NPs) functionalized with amine groups via amid links (SiN-NH-PAG). Additional Features include high photo-acid quantum yield, high one-photon (1PA) and two-photon absorption (2PA) with low fluorescence quantum yield. In vivo, confocal microscope studies with HCT-116 (Human colorectal carcinoma) cancer cells showed that photodynamic processes in the presence of PAG were completed under one- photon absorption (1PA) conditions. In these experiments, cells were imaged at 1 min intervals for a total of 4 hours with the aid of Differential Interference Contrast (DIC). Among the photodynamic therapy agents tested via cytotoxicity experiments with the MTS assay, (SiN-NH- PAG) showed the best efficiency to induce cell death. The increased effectiveness of the new agent is probably due to the large number of PAG groups present on the surface of Si NPs.iiLysosome colocalization indicates that PAGs are mainly built in lysosomes. The increase of acidic content inside the lysosome was demonstrated with the aid of the LysoSensor Green probe. The drop in the intralysosomal pH was approximately 0.3 units. This is a desirable outcome as most cells underwent necrosis at pH ? 4.4. For clinical diagnosis purposes, a biochemical sensor was developed for the analysis of phosphate ions in urine samples. Abnormal levels of inorganic phosphate in human urine samples are related to the development of certain types of cancers affecting several organs of the human body, including breast, pancreas, lung and thyroid. The new biochemical sensor is based on the fluorescence energy transfer between a lanthanide luminescent probe [Tb-EDTA]-1 and gold nanoparticles (Au NPs) capped with a Cetyltrimethylammonium bromide (CTAB) micelle. With this approach, it was possible to selectively determine inorganic phosphate (Pi) in urine samples at the micro-molar concentration level. Urine samples collected from healthy, non-smoking individuals showed no interference from concomitants usually found in human urine samples. The simplicity of analysis provides an approach well-suited for (")real-time(") monitoring of phosphate ions. Analysis time is made possible within approximately 10 min per sample.
Show less - Date Issued
- 2016
- Identifier
- CFE0006528, ucf:51384
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006528
- Title
- THE EFFECT OF COLLOIDAL STABILITY ON THE HEAT TRANSFER CHARACTERISTICS OF NANOSILICA DISPERSED FLUIDS.
- Creator
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Venkataraman, Manoj, Kumar, Ranganathan, University of Central Florida
- Abstract / Description
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Addition of nano particles to cooling fluids has shown marked improvement in the heat transfer capabilities. Nanofluids, liquids that contain dispersed nanoparticles, are an emerging class of fluids that have great potential in many applications. There is a need to understand the fundamental behavior of nano dispersed particles with respect to their agglomeration characteristics and how it relates to the heat transfer capability. Such an understanding is important for the development and...
Show moreAddition of nano particles to cooling fluids has shown marked improvement in the heat transfer capabilities. Nanofluids, liquids that contain dispersed nanoparticles, are an emerging class of fluids that have great potential in many applications. There is a need to understand the fundamental behavior of nano dispersed particles with respect to their agglomeration characteristics and how it relates to the heat transfer capability. Such an understanding is important for the development and commercialization of nanofluids. In this work, the stability of nano particles was studied by measuring the zeta potential of colloidal particles, particle concentration and size. Two different sizes of silica nano particles, 10 nm and 20 nm are used in this investigation at 0.2 vol. % and 0.5 vol. % concentrations. The measurements were made in deionized (DI) water, buffer solutions at various pH, DI water plus HCl acid solution (acidic pH) and DI water plus NaOH solution (basic pH). The stability or instability of silica dispersions in these solutions was related to the zeta potential of colloidal particles and confirmed by particle sizing measurements and independently by TEM observations. Low zeta potentials resulted in agglomeration as expected and the measured particle size was greater. The heat transfer characteristics of stable or unstable silica dispersions using the above solutions were experimentally determined by measuring heat flux as a function of temperature differential between a nichrome wire and the surrounding fluid. These experiments allowed the determination of the critical heat flux (CHF), which was then related to the dispersion characteristics of the nanosilica in various fluids described above. The thickness of the diffuse layer on nano particles was computed and experimentally confirmed in selected conditions for which there was no agglomeration. As the thickness of the diffuse layer decreased due to the increase in salt content or the ionic content, the electrostatic force of repulsion cease to exist and Van der Waal's force of agglomeration prevailed causing the particles to agglomerate affecting the CHF. The 10nm size silica particle dispersions showed better heat transfer characteristics compared to 20nm dispersion. It was also observed that at low zeta potential values, where agglomeration prevailed in the dispersion, the silica nano particles had a tendency to deposit on the nickel chromium wire used in CHF experiments. The thickness of the deposition was measured and the results show that with a very high deposition, CHF is enhanced due to the porosity on the wire. The 10nm size silica particles show higher CHF compared to 20nm silica particles. In addition, for both 10nm and 20nm silica particles, 0.5 vol. % concentration yielded higher heat transfer compared to 0.2 vol. % concentration. It is believed that although CHF is significantly increased with nano silica containing fluids compared to pure fluids, formation of particle clusters in unstable slurries will lead to detrimental long time performance, compared to that with stable silica dispersions.
Show less - Date Issued
- 2005
- Identifier
- CFE0000837, ucf:46676
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000837
