1999 Research Abstracts
JULY 2, 1999
Patel, Anup. 1999. The Effect of Ethanol Preexposure on Ethanol-induced Conditioned Taste Aversion. Baylor University. Dr. Jaime Diaz-Granados (Department of Psychology and Neuroscience) & Danielle Graham.
Drugs produce severe consequences in humans by disrupting vital biological functions. Tolerance arises from biological changes that reduce the averse conditions of the drugs, while promoting further drug consumption. Tolerance to a drug may, however, promote a weak taste aversion. Adolescents may develop a strong tolerance to alcohol as their consumption increases. This study investigates the effects of adolescent ethanol exposure on the adult's conditioned taste aversion response. A preexposure effect states that, after receiving preexposure to an unconditioned stimulus (e.g. ethanol), after conditioning, the association between the conditioned stimulus (e.g. saccharin) and the unconditioned stimulus is reduced. One group of adolescent mice was preexposed to ethanol for 64 hr via inhalation, while another was placed in the same chamber for inhalation, but did not receive any ethanol. After six weeks, the conditioned saccharine stimulus was paired with the unconditioned stimulus. Following conditioning, we measured the intake of saccharine for 30 min/day for 3 days. Less saccharine consumption indicated a strong conditioned taste aversion, while increased consumption indicated a weak conditioned taste aversion. These results suggest that adolescent mice that received preexposure developed a weaker conditioned taste aversion, compared to the adolescent mice that did not receive preexposure. This suggests that exposure to alcohol in adolescence will produce a greater tolerance to it in adulthood. Additionally, preexposure lasted up to six weeks, contrary to other studies suggesting that preexposure is only effective for a maximum of 94 hr. Future research needs to be conducted on the biological changes that occur to produce a preexposure effect in adolescents.
Beta-turns have become an increasingly important topic of biochemistry in recent times. These are located in the folds of secondary structures of proteins and play an important role in the manipulation of cell division. Some beta-turn mimics, or artificially synthesized beta-turns, have been known to inhibit tubulin polymerization, which is crucial in cell division. In an effort to suppress the multiplication of cancer cells, beta-turn mimics were synthesized to replace the actual beta-turns. During my stay at Baylor University, I synthesized the basic structure of a beta-turn mimic with dibenzofuran, or DBF. This compound was then manipulated to produce a di-acid of DBF, which will serve as a base for other analogs. Although many different anti-cancer drugs can be produced from this base, I synthesized one novel compound, SWC I-30. During the course of this four-step synthesis, various techniques were used (i.e. capillary gas chromatography, nuclear magnetic resonance, etc.) to ensure the purity and structure of each compound. SWC I-30 is undergoing synthesis as of the publication of this abstract. After purification, the new compound will be given to the Pettit group at Arizona State University for tubulin polymerization inhibition.
One current area of interest concerning the research of anti-cancer drugs involves the inhibition of mitosis. Mitosis is a process by which cells reproduce. During the metaphase of mitosis, chromosomes begin to separate. This separation is facilitated by microtubles, which are made up of tubulin; tubulin molecules polymerize to form the microtubules. By inhibiting the polymerization of tubulin and thus the formation of microtubules, metaphase can be inhibited. This then prevents the completion of the cell cycle. By controlling the polymerization and depolymerization of tubulin in cancerous cells, the growth of the cancerous cells can be inhibited. This has done by adding ligands to the tubulin units; the ligands hinder the polymerization. Certain anticancer agents have already been developed such as Tamoxifen, an anti-estrogen, Combretastatin A-4 (CSA-4), a prodrug. My research goal involved synthesizing Tamoxifen derivatives with CSA-4 moiety. I have synthesized several molecule that can be used to further synthesize molecules that resemble Tamoxifen molecule. Such molecules then have a possibilty of undergoing cytotoxicity tests.
Common properties of substances are not always so common. While typically similar electrical and structural properties are found throughout a substance, those same properties can often vary widely at the surface of the sample. In the Laboratory for Surface Analysis and Modification, we use electrons, ions, and x-rays combined with an ultra high vacuum to explore the surfaces of samples. Through interpretation from our data we can learn a lot about the atoms of our sample, such as its bonding structure, how it interacts with other elements, and what electrical properties it possesses. Specifically, I have been working with Molybdenum Disulfide (MoS2). MoS2 is worthy of study because it is a transition metal chalcogenide. This means that MoS2 is in a class of material in which minor discrepancies in atomic structure exhibit huge variations in magnetic, optical, chemical, electrical, and structural properties. If we can better understand the structure, electrical nature, and the way it interacts with other elements, (like alkali metals) then we will be able to fine-tune MoS2 in a way that will fit technical needs varying from more efficient circuit boards, to capacitors which hold more charge.
Organic chemistry is the chemistry of molecules containing carbon, usually bonded to hydrogen, nitrogen, or both. Much of the research activity in organic chemistry is in applied science, to develop or discover new molecules, techniques, or processes for practical purposes. One such area of research is synthetic chemistry, the combining of pre-existing chemicals and compounds into new compounds. My work combined a benzomide ring compound in two different amines to form two separate organic molecules. Techniques used included TLC (thin layer chromatography), flash column chromatography, HPLC (high-pressure liquid chromatography), gas chromatography/mass spectroscopy, and NMR (nuclear-magnetic resonance spectroscopy). Both reactions seem to have worked, and formed the expected compounds. Determining whether the compounds will have the hoped-for chemotherapeutical properties will take extensive testing, and is beyond the scope of this project.
York, Ana. 1999. Wolfe City Trace Fossils. Baylor University. Dr. Rena Bonem (Department of Geology)
This project focuses on the use of trace fossils and other environmental indicators to determine the depositional environment of the Wolfe City Sands. Two contrasting interpretations have been proposed for the depositional environment. One suggests shallow water while the other suggests near abyssal depths. The Wolfe City Sand is a member of the Taylor Group in the upper cretaceous period. It is composed of alternating layers of sandy shale and shaley sands, with an occasional resistant sandstone ledge. The studied outcrop is along the banks of Deer Creek east of Waco. Many environmental indicators lead to different conclusions in this study. Some trace fossils found could represent either a deep or stressed shallow water environment. The abundance of anemones provides evidence that the environment was within the photic zone. The presence of heavy minerals suggests deposition in shallow water along a shoreline. However, bone beds, similar to the zone of accumulation containing shark teeth and turtle bone fragments, often indicate deposition in deeper water. Other body fossils such as the plesiosaur tooth, the bivalves, and one gastropod suggest a shallow waster depositional environment. A microscopic evaluation showed frosted grains indicating a close proximity to the shore. Samples from surrounding rock units suggest shallow water deposition. Based on observations made during the course of this investigation, it is most likely that the environment of deposition of the Wolfe City Sands was deltaic. Additional fieldwork at other localities could provide definitive evidence of water depth.
Laboratory experiments are one fo the most important aspects of teaching organic chemistry. Effective labs will reinforce concepts best if they include creative yet practical chemistry and useful procedures while also maintaining ties to the real world. My research this summer dealt with the development and modification of two experiments for advanced organic chemistry laboratory. The first project was to find a reproducible and simple procedure for an experiment that had originally used very water-sensitive and difficult-to-handle tert-butoxide to promote an aromatic substitution with chlorotoluenes. Several methods were attempted but problems with each prevented the identity of a usable procedure. The second experiment dealt with the development of a new chemistry of azulenes, an interesting group of higly colored aromatic compounds containing a parent cyclopentanecycloheptane (C10H8) structure. The research completed this summer adds to the current azulene lab with our attempts to prepare oxime and hydrazone derivatives of trifluroacetylazulene, the final product of the current lab. Additionally, an interesting metellation/cyclization reaction that created a colorful fluorinated tricyclic alcohol may lead to the synthesis of new dicyclized azulene compounds. The research completed this summer has not only improved my understanding of organic chemistry, but might also aid future students.
It is estimated that the earth's supply of fossil fuels will become scarce and highly expensive by the year 2010. Alcohols have proven to be one of the best substitutes for gasoline in automobiles, which account for about 40% of the world's fuel usage. Specifically, ethanol is regarded as the best alcohol to replace gasoline in the near future, as opposed to methanol and other non-renewable contenders. Ethanol must be fermented by certain species of yeast who require glucose to live. Research pertaining to ethanol fuel usage focuses on hydrolysis, a way to get the glucose simply, and economically from renewable sources such as biomass. My research focused on using orange peels as a source of sugar. The hypothesis is that the natural acids in citrus waste will be able to hydrolyze the cellulose into glucose without the addition of enzymes or acids. This would greatly reduce the cost of pretreatment in the future. I attempted to find the optimum temperature which would yield the highest percentage of sugars, without caramelizing/destroying them. A range of temperatures from 100 - 230 C at 2.5, 5, and 10 minutes were tested. Results suggest that sugars are lost at 220 C, thus making the optimum temperature between 200 and 220 C. Once a well working method is developed for the pretreatment of citrus waste, it may supplement corn and wood as the main sources of cellulose for ethanol production. The use of ethanol fuel will become increasingly important in the upcoming years as fuel becomes a scarce and isolated resource.
Spectroscopy has been in use since the days of Bunsen with his flames and prisms. Today, it is a very reliable way to identiry unknown materials. Because each element or compound has a specific absorption or emission spectrum, spectroscopy allows us to pinpoint that material. I helped with the lab setup, including alignment and working with the equipment. I also helped run experiments and analyze data we gathered. By using the laser system to analyze a neon-filled tube, we obtained results nearly identical to published results. These results also helped us to better align the laser. Work such as this will become increasingly important in the future, as we need to learn about the chemical composition of a greater number of places. Specifically, one example is the search for another habitable planet -- by knowing what to look for in a system, we can analyze visual data (as well as data sent from other probes) to determine the chemical makeup of a system.
Often, when things are made fire-resistant, a fire-resistant material is used as a coating. These coatings tend to be toxic or harmful to the environment. My assignment was to synthesize a polymeric fiber, or plastic, that was similar to polyester, fire-resistant, and not harmful to the enviroment. The idea was to combine the fiber-forming properties of poly(ethylene terephthalate (a.k.a. polyester), a flammable fiber, with poly(methylene oxalate), a non-flammable substance to form a fiber that would be fire-resistant and enviromentally friendly. I successfully prepared one combination of the two as a copolymer. With more research, a more suitable combination may be prepared that could be useful for clothing, upholstery, carpets and possibly even the space program.
A common, yet devastating, experience in a student's career is the disappointment felt after receiving a not-so-stellar score on a test he was so sure he had aced. My purpose this summer was to explain why a students' perception of their performance is usually inconsistent with their actual performance on standardized tests - and possibly to derive a solution to this frustrating problem which could become crucial in instances students are given the choice of canceling or keeping their scores on record. I hypothesized that there was a relationship between the familiarity of answer choices, confidence levels and test performance. Using a multiple-choice test I designed with this in mind, I experimented with 20 students and found that subjects were typically just as confident when choosing the correct answer as they were when choosing the familiar but incorrect answer. Familiarity does affect confidence levels. Possible solutions include attempting to answer test questions without looking at the answer choices beforehand.