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Gas phase conversion of sugars to valuable C3 chemicalsYan, Wei, January 2008 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 31, 2009) Includes bibliographical references.
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In Vitro Exploration of Functional Acrolein Toxicity with Cortical Neuronal NetworksDurant, Stormy R. 05 1900 (has links)
Acrolein is produced endogenously after traumatic brain injury (TBI) and is considered a primary mechanism for secondary damage occurring after TBI. We are using frontal cortex networks derived from mouse embryos and grown on microelectrode arrays in vitro to monitor the spontaneous activity of networks and the changes that occur after acrolein application. Networks exposed to acrolein exhibit a biphasic response profile. An initial increase in network activity, followed by a decrease to 100% activity loss in applications ≥ 50 µM. In applications below 50 µM, acrolein was not toxic but generated activity instability with coordinated but irregular population busts lasting for up to 6 days. The increase in activity preceding toxicity may be linked to a decrease in free spermine, a free radical scavenger that modulates Na+, K+, Ca+ channels as well as NMDA, Kainate, and AMPA receptors. Action potential wave shape analysis after 20 and 30 µM acrolein application revealed a concentration-dependent 15-33% increase in peak to peak amplitude within minutes after exposure. For the same concentrations of acrolein (50 µM), the time required to reach 100% activity loss (IT100) was longer in serum-free medium than in medium with 5% serum, in which IT100 values were reduced by a factor of 4. The greater toxicity in the presence of serum may be explained by acrolein adducts on serum proteins. These reaction products have been shown by other labs to be toxic in cell culture. This in vitro system could be used to expand biochemical analyses such as acrolein-induced spermine depletion and may provide an effective platform for investigating cell culture correlates of secondary TBI damage.
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ROLE OF ACROLEIN IN NEUROTRAUMA AND RELATED NEURODEGENERATIONSeth A Herr (10712604) 06 May 2021 (has links)
Neurotrauma is a general term describing injury to the central nervous system (CNS); which comprises of the brain and spinal cord. The damage resulting from neurotrauma includes primary injury, which occurs from different sources such as compressed air hitting the brain (bTBI) or an object/bone contusing the spinal cord, resulting in a spinal cord injury (SCI). These various means of primary brain and spinal cord injury are further complicated by the many possible combinations of severity levels and frequencies. However, primary injuries are regarded in many cases as unavoidable with the immediate nerve damage being largely irreversible. Despite all this, primary injuries of the CNS are related by common biochemical pathways in secondary injury. Secondary injury is the cause of declining outcomes after neurotrauma and poor recovery. Secondary injury begins immediately after primary injury and can continue to trigger death of neurons for years later. Given this contribution to poor recovery and its slow progression, secondary injury provides an excellent window of opportunity for therapeutic intervention. A major factor and key link in secondary injury and its perpetuation is reactive aldehyde formation, such as acrolein, from lipid peroxidation. The common formation of acrolein in neurotrauma is attributed to the unique structure of the CNS: with neurons containing a high lipid content from myelin and heavy metabolic activity they are vulnerable to acrolein formation. Thus, acrolein in secondary injury is a point of pathogenic convergence between the various forms of neurotrauma, and may play a role as well in the development of neurotrauma linked disorders and related neurodegeneration. The overall goal of this thesis is to therefore develop better strategies for acrolein removal. We explore here endogenous clearance strategies and targeted drug delivery in SCI, investigate detailed cellular structure changes in bTBI, and acrolein formation and removal in Parkinson’s disease. These findings of pathology, and effectiveness of new or existing acrolein removal strategies, will allow us to better employ treatments in future studies.
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ANALYTICAL METHOD DEVELOPMENT FOR THE DETECTION AND ANALYSIS OF PROTEIN CARBONYLSCoffey, Chelsea M 01 January 2015 (has links)
Oxidative stress can result in changes to many biomolecules and also affect their activities. We are interested in protein carbonylation, a type of unnatural oxidation which has been associated with numerous degenerative disease states and is also a consequence of the natural aging process. Protein carbonyls are stable species, but countless analytical barriers exist in terms of their identification. Thus, the main goal of this work was to develop and optimize analytical methods that could be used to help us better understand which, where, and how proteins are being carbonylated.
Initial studies involved method validation for carbonylating, tagging, and enriching the model protein human serum albumin (HSA). We have developed a reproducible method of producing carbonylated protein in vitro in which HSA is treated with acrolein to carbonylate cysteines, histidines, and lysines. Protein carbonyls are compatible with various affinity labels and enrichment techniques. We strived to learn more about the efficiencies of various biotin affinity labels and avidin enrichment techniques using quantitative assays and mass spectrometry. Results showed a preference for different affinity labels based on their chemical properties and suggested that monomeric columns are selective for particular peptides. Most recently, method development and validation work was done involving a cleavable biotin tag that enables both enrichment and identification of protein carbonylation modification sites. This affinity tag offered the highest labeling efficiency of all tags tested in the past and greater coverage of modification sites than biotin hydrazide reagents.
We applied our analytical methods to two sets of human blood samples. The first sample set was plasma taken from chronic kidney disease (CKD) patients. No carbonylation patterns were elucidated, but this project marked the beginning of blood analyses in which existing protocols were adapted to blood samples. The second sample set was serum/plasma taken from patients with traumatic injuries. We effectively applied our analytical methods to these sample sets and were able to visualize and quantitate temporal protein carbonylation patterns via Western blotting and iTRAQ-based mass spectrometry experiments. ProteoMiner experiments proved successful in that we were able to identify a larger and more diverse amount of carbonylated proteins via mass spectrometry.
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Selective oxidation of propylene to acrolein over vanadium and niobium doped bismuth molybdatesLi, Xin. January 2009 (has links)
Thesis (M.Ch.E.)--University of Delaware, 2008. / Principal faculty advisors: Mark A. Barteau and Douglas J. Buttrey, Dept. of Chemical Engineering. Includes bibliographical references.
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The Influence of Oxygen Tension and Glycolytic and Citric Acid Cycle Substrates in Acrolein-induced Cellular Injury in the Differentiated H9c2 Cardiac Cell ModelCoyle, Jayme 04 November 2016 (has links)
Most in vitro systems employ the standard cell culture maintenance conditions of 95 % air with 5 % CO2 to balance medium pH, which translates to culture oxygen tensions of approximately 20 % - above the typical ≤ 6 % found in most tissues. The current investigation, therefore, aims to characterize the effect of maintenance and toxicant exposure with a particular focus on the α,β-unsaturated aldehyde, acrolein, in the presence of physiologically relevant oxygen tension using a differentiated H9c2 cardiomyoblast subclone. H9c2 cells were maintained separately in 20.1 and 5 % oxygen, after which cells were differentiated for five days, and then exposed to acrolein in media containing varying concentrations of tricarboxylic acid and glycolytic substrates. Cells were then assessed for viability and metabolism via the MTT conversion assay. H9c2 cells were assessed for mechanistic elucidation to characterize contributors to cellular death, including mitochondrial membrane potential (ΔΨm) reductions (JC-1), intracellular calcium influx (Fluo-4), and PARP activation. Exposure to acrolein in differing oxygen tensions revealed that standard culture cells are particularly sensitive to acrolein, but cells cultured in 5 % oxygen, depending on the medium pyruvate concentration, can be rescued significantly. Further, reductions in ΔΨm were reversed by co-exposure of 5-10 mM EGTA for both culture conditions, while intracellular calcium transients were noted only for standard cultures. The results demonstrate significant metabolic reprogramming which desensitizes differentiated H9c2 to acrolein-induced cytotoxicity. Further, PARP and extracellular calcium contribute to the fate of these cells exposed to acrolein, though clotrimazole-associated TRPM2 channels may not be significantly involved. Conclusively, significant alteration of toxicogenic response was noted in this cell line when cultured under physiologically relevant conditions, and may have a substantial impact on the reliability and predictive power and interpretive application of in vitro-based toxicity models cultured under standard culture conditions, depending on the parent tissue.
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Assessment of Acrolein-induced Toxicity Using In-vitro Modeling to Evaluate the Role of PARP Inhibitors in Reducing CytotoxicityHarand, Kristina Marie 23 March 2016 (has links)
Acrolein is an electrophilic α, β-unsaturated aldehyde. Additionally, acrolein is a metabolite of the antineoplastic alkylating agent cyclophosphamide and is implicated in off-target effects, including to bladder hemorrhagic cystitis and cyclophosphamide-induced cardiotoxicity, both of which have led to serious secondary iatrogenic injury during and following chemotherapy. At low concentrations acrolein inhibits cell proliferation without inducing apoptosis, while at high concentrations may result in secondary apoptosis promotion. This investigation assessed the role of the enzyme poly (ADP-ribose) polymerase (PARP) in acrolein induced toxicity using the established toxicological H9c2 (2-1) cardiomyoblast in vitro model. H9c2 (2-1) cells were plated in 24-well plates at 75,000 cells per well three days prior to testing, followed by acrolein dosing at concentrations between 10 µM and 1000µM for either 30 or 55 minutes. PARP activity was quantitatively measured in total cell lysates using a biotin-avidin-conjugated horseradish peroxidase-TMB reporter system in a 96-well microplate formate. The lowest effective dose of toxicity at 30 minute dosing was found at 25 μM (PARP Activity 1.65-fold control) which returned to baseline at 100 μM; concentrations at or above 250 μM results in significant PARP activity reductions (≤ 0.46-fold control). Biomarkers were further characterized for cytotoxicity (AST presence), and viability (MTT reduction) in order to facilitate mechanistic characterization of PARP-mediated acrolein cardiotoxicity. Investigation of a PARP inhibitor was assessed to explore the intervention for acrolein induced cardiac tissue damage.
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Assessment of the Role of Poly (ADP-Ribose) Polymerase in Drug-Induced CardiomyopathyBrinkerhoff, Alexis I. 23 March 2016 (has links)
Drug-induced cardiotoxicity has resulted in a thorough evaluation of patient doses, treatments, and rehabilitation. One of the most commonly prescribed chemotherapeutic agents is cyclophosphamide. The active metabolite, acrolein, is one of the most potent inducers of cardiomyopathy. In this study, research was conducted on the H9c2 (2-1) cardiomyocyte cell line derived from the embryonic myocardium of rattus norvegicus to assess its competency for evaluation of the change in poly (ADP-ribose) polymerase (PARP) activity. The application of this model to study the effects of acrolein on PARP activation was chosen as an ideal determinant of cell damage produced by nitrogen mustards. To verify the legitimacy of this model, cardiomyocytes were exposed to acrolein in varying concentrations and time durations with a subsequent protein concentration measurement determined through the BCA Protein Assay. After the normalization of samples through volume adjustments and verification of sufficient protein, other aliquots were subjected to a PARP Assay in order to measure PARP activity. PARP was activated at exposure concentrations of 75 μM in all trials, with an average detection of 0.00569 ± 0.001 mU/200ng protein. Other concentrations showed varying degrees of PARP activation, verifying the model’s competency. PARP activation implies the potential use of this model for further research into targeted molecular therapy of PARP inhibition. Therefore, this model has the ability to be used as an assessment tool for the combined use of PARP inhibitors and chemotherapeutic agents; it can be useful for future research investigating the use and efficacy of PARP inhibitors in reducing drug-induced cardiotoxicity.
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Selective oxidation of propene to acrolein on α-Bi₂Mo₃O₁₂ nano-particlesVan Vuuren, Peter 03 1900 (has links)
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2005. / Although selective oxidation catalysts are widely used and extensively studied for their
industrial and academic value, their complex mechanisms are, to a large extent, still
unclear. The field of so-called allylic (amm)oxidations reactions was chosen for further
investigation, in particular the simplistic selective oxidation of propene to acrolein over an
α-Bi2Mo3O12 catalyst.
One of the most important approaches in selective oxidation is to try to correlate the
physicochemical properties of catalysts with their catalytic performance (activity and
selectivity). The most interesting, and seemingly most widely invoked parameter, is
lattice oxygen mobility. The problem, however, is the difficulty encountered in measuring
oxygen mobility.
It is hypothesised that the depth of oxygen utilisation and lattice oxygen mobility of
bismuth molybdate during the partial oxidation of propene to acrolein may be determined
by measuring the rate of acrolein formation and lattice oxygen usage over a range of
discrete particle sizes that could be synthesised using reverse micelle technology.
Catalyst Preparation
A preliminary investigation into the reverse micelle technique showed that discrete nanosized
particles could be synthesised, but that there was no size control over the outcome
and that, in most cases there were some degree of particle agglomeration. It was also
found that nanorod formation occurred due to adsorbtion of surfactant. More in-depth
investigation had to be done in order to achieve particle size control and the liberation of
the calcined α-Bi2Mo3O12 catalyst particles required for kinetic experiments. Simple
precipitation methods, the catalyst calcination step, and the formation and stability of
reverse micelles were investigated.
A simple precipitation method to prepare α-Bi2Mo3O12, suitable to be integrated into the
reverse micelle technique was found by buffering the mixture of bismuth nitrate and
ammonium molybdate solutions with an excess of molybdate. This prevented the pH
from decreasing below a critical value of 1.3 (at which β-Bi2Mo2O9 forms as an impurity). The excess molybdenum caused the formation of MoO3 in the calcined product, which
was selectively and successfully removed using a warm ammonium wash followed by a
water rinse and a recalcination step.
XRD of a temperature range calcination shows that the calcination starts at temperatures
as low as 200°C and almost complete calcination of the catalyst at 280°C. DSC analyses
show a 47.15 J/g crystal formation peak only at 351°C. The Mo18O56(H2O)8
4- anion or its
double, Mo36O112(H2O)16
8-, is responsible for the formation of α-Bi2Mo3O12 in the
precipitation calcination reaction.
Reverse micelles were investigated using a Malvern Zetasizer and showed a complex
dynamic system in which the reverse micelle sizes and size distributions change over
time as a function of surfactant and aqueous concentrations, the salt used and aqueous
phase salinity. Although much was accomplished in this study, more investigations into
the constituent steps of the reverse micelle technique are needed to develop a method
to synthesise the range of discrete catalyst particle sizes required for kinetic studies.
Kinetic Studies
For the purpose of kinetic experiments a metal reactor was found to be superior to that
of a glass reactor. The reactor rig was adequate for these kinetic studies but do not meet
the requirements for detailed reaction order experiments. The analysing apparatus could
not measure CO2 formation accurately and it had to be calculated using a carbon
balance.
Only the model proposed by Keulks and Krenzke [1980a] was able to describe the kinetic
result, but the model parameter describing the oxidative state of the catalyst surface
could not be calculated due to the lack compatibility between published data. Values
were awarded to this parameter so to give an Arrhenius plot which corresponded to
published data. The parameter describing the oxidative state vs. temperature took on a
function that was consistant with the reasoning of Keulks and Krenzke [1980a].
Comprehensive preliminary kinetic studies are needed, both in catalyst reduction and reoxidation,
in order to determine the reaction conditions, explore more advanced kinetic
models and investigate model parameters that are theoretically and/or empirically
obtainable and quantifiable.
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Acolein in wine : bacterial origin and analytical detectionBauer, Rolene 03 1900 (has links)
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT:
Wine quality is compromised by the presence of 3-hydroxypropionaldehyde (3-HPA)
due to spontaneous conversion into acrolein under wine making conditions. Acrolein
is highly toxic and is presence has been correlated with the development of
bitterness in wine. Lactic acid bacterial strains isolated from South African red wine,
Lactobacillus pentosus and Lactobacillus brevis, are implicated in accumulating 3-
HPA during anaerobic glycerol fermentation. The environmental conditions leading
to its accumulation are elucidated. In aqueous solution 3-HPA undergoes reversible
dimerization and hydration, resulting in an equilibrium state between different
derivatives. Interconversion between 3-HPA derivatives and acrolein is a complex
and highly dynamic process driven by hydration and dehydration reactions. Acrolein
is furthermore highly reactive and its steady-state concentration in complex systems
very low. As a result analytical detection and quantification in solution is problematic.
This study highlights the roles played by natural chemical derivatives and shows that
the acrolein dimer can be used as a marker for indicating the presence of acrolein in
wines. Solid-phase microextraction (SPME) coupled to gas chromatograph mass
spectrometry (GC-MS) was validated as a technique for direct detection of the
acrolein dimer in wine. The potential of a recently introduced sorptive extractive
technique with a sample enrichment probe (SEP) was also investigated. The SPME
technique simplifies the detection process and allows for rapid sampling of the
acrolein marker, while SEP is more sensitive. / AFRIKAANSE OPSOMMING:
Die teenwoodigheid van 3-hidroksiepropioonaldehied (3-HPA) in wyn het ‘n
negatiewe invloed op kwaliteit as gevolg van die moontlike omskakeling na akroleien
tydens die wynmaak prosses. Akroleien is hoog toksies en is moontlik betrokke by
die ontwikkeling van ‘n bitter komponent in wyn. Hierdie studie wys dat stamme van
die melksuurbakteriëe Lactobacillus pentosus en Lactobacillus brevis, geisoleer uit
Suid-Afrikaanse wyn, 3-HPA tydens anaerobiese alkoholiese fermentasie kan opbou.
Kondisies wat ontwikkeling beinvloed is bestudeer. 3-HPA ondergaan omkeerbare
dimerisasie en hidrasie in oplossing en het ‘n ewewig tussen veskillende derivate tot
gevolg. Omkakeling tussen 3-HPA derivate en akroleien is ‘n komplekse en hoogs
dinamiese prosses wat gedryf word deur hidrasie en dehidrasie reaksies. Akroleien
is verder hoogs reaktief en die ewewigskonsentrasie van hierdie aldehied in
komplekse omgewings is laag. Analitiese waarneming en kwantifisering is gevolglik
problematies. Hierdie studie lig die rol wat natuurlike chemise derivate speel duidelik
uit en wys dat die akroleien dimeer as ‘n merker gebruik kan word om die
teenwoodigeid van akoleien in wyn te staaf. Soliede-fase mikro-ekstraksie (SPME)
gekoppel aan gas chromatografie massa spektroskopie (GC-MS) is gevalideer as ‘n
tegniek vir die direkte waarneming van die akroleien dimeer in wyn. Die potensiaal
van ‘n nuwe ekstraksie tegniek, gebasseer op ‘n peiler wat vir die monster verreik
(SEP), was ook ondersoek. Die SPME tegniek is vinnig en vergemaklik analiese,
terwyl SEP meer sensitief is.
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